# Full Text: AntConsciousness

> Extracted from `2019_AntConsciousness.pdf`

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https://doi.org/10.1007/s11229-019-02130-y
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The ant colony as a test for scientific theories 
of consciousness
Daniel A. Friedman1   · Eirik Søvik2 
Received: 15 June 2018 / Accepted: 7 February 2019 / Published online: 12 February 2019 
© Springer Nature B.V. 2019
Abstract
The appearance of consciousness in the universe remains one of the major mysteries 
unsolved by science or philosophy. Absent an agreed-upon definition of conscious-
ness or even a convenient system to test theories of consciousness, a confusing het-
erogeneity of theories proliferate. In pursuit of clarifying this complicated discourse, 
we here interpret various frameworks for the scientific and philosophical study of 
consciousness through the lens of social insect evolutionary biology. To do so, we 
first discuss the notion of a forward test versus a reverse test, analogous to the nor-
mal and revolutionary phases of the scientific process. Contemporary theories of 
consciousness are forward tests for consciousness, in that they strive to become a 
means to classify the level of consciousness of arbitrary states and systems. Yet no 
such theory of consciousness has earned sufficient confidence such that it might be 
actually used as a forward test in ambiguous settings. What is needed now is thus a 
legitimate reverse test for theories of consciousness, to provide internal and exter-
nal calibration of different frameworks. A reverse test for consciousness would ide-
ally look like a method for referencing theories of consciousness to a tractable (and 
non-human) model system. We introduce the Ant Colony Test (ACT) as a rigorous 
reverse test for consciousness. We show that social insect colonies, though disag-
gregated collectives, fulfill many of the prerequisites for conscious awareness met by 
humans and honey bee workers. A long lineage of philosophically-neutral neurobe-
havioral, evolutionary, and ecological studies on social insect colonies can thus be 
redeployed for the study of consciousness in general. We suggest that the ACT can 
provide insight into the nature of consciousness, and highlight the ant colony as a 
model system for ethically performing clarifying experiments about consciousness.
Keywords  Consciousness · Social insects · Ants · Bees · Ant colony · Philosophy of 
science · Scientific theories of consciousness
 *	 Daniel A. Friedman 
	
danielarifriedman@gmail.com
1	
Department of Biology, Stanford University, Stanford, CA, USA
2	
Department of Science and Mathematics, Volda University College, Volda, Norway

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1  Introduction: scientific study of consciousness
1.1  Rewards and challenges for scientific theories of consciousness
Human beings are conscious. Few non-philosophers find this statement conten-
tious. Each healthy human being on this planet, presumably by virtue of their 
central nervous system (e.g. as opposed to their teeth), has an ongoing subjective 
experience. Yet no scientific or philosophical consensus exists on what exactly 
consciousness is, or which physical systems are conscious (Van Gulick 2018). A 
successful theory of consciousness should provide unique explanations and test-
able predictions about phenomenal consciousness, and ideally would not suffer 
from unwarranted anthropocentric biases. Such a theory could be used to deter-
mine which systems possess what kind of awareness (equivalent to phenomeno-
logical consciousness, as described later). Using theory to resolve the phenom-
enological status of various human states (e.g. dreaming, fetus, adult in coma), 
animals (e.g. dogs, cows, insects), and non-biological systems (e.g. computers, 
countries, ant colonies) would have a tremendous impact on practical ethics. 
However, no such scientific theory of consciousness has risen to a level of sophis-
tication, coherence, or utility that would allow it to be used in such a “test-like” 
fashion (Schwitzgebel 2018a; Van Gulick 2018). Further complicating the picture 
is that the contemporary diversity of theories of consciousness are heterogeneous 
in their axioms, structure, predictions, and implications. This makes comparisons 
between theories currently difficult, if not simply irrelevant.
No single definition exists for Consciousness—we here discuss phenomeno-
logical awareness. Nuanced pluralistic frameworks exist for the study of observ-
able biological phenomena such as animal behavior (Longino 2000, 2013; Mitch-
ell 2002). However, the scientific study of consciousness is specifically hindered 
from reaching a state of coherent pluralism due to a heterogeneity of definitions 
for “consciousness” (Morin 2006; Bayne et  al. 2016; Fazekas and Overgaard 
2016; Dehaene et al. 2017; Smith 2018; Van Gulick 2018). Despite the murkiness 
of the term itself, two types of “consciousness” can be differentiated: phenome-
nological consciousness and access consciousness (Block 1995a, b). Phenomeno-
logical consciousness refers to the experience of consciousness, consisting of the 
private and subjective experiences (qualia) that an entity might be having (Nagel 
1974; Toadvine 2018). This sort of conscious awareness, at least sometimes, 
exists in adult humans (Nagel 1974; Searle 2002; Koch et al. 2016; Tononi et al. 
2016; Goff 2017, but see Aaronson 2014; Dennett 2001). Access consciousness 
more mundanely refers to the ability of a stimuli to influence the future actions of 
the biological system (e.g. via eliciting a self-report or motor behavior), without 
making any claims about whether a subjective experience arises from the stimuli 
(Block 1995b, 2007). For example, subliminal stimuli enter access consciousness 
but not phenomenological consciousness, because we can be influenced by such 
stimuli but are not aware of their perception. Here we focus on phenomenologi-
cal consciousness rather than mere access consciousness, and consider whether 
diverse systems might genuinely have such awareness.

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The “Hard Problem” makes things hard The famously-intractable “Hard Prob-
lem of consciousness” is a question about how consciousness arises from physical 
matter (Chalmers 2017), essentially asking which kinds of physical materials might 
be capable of hosting conscious awareness (e.g. neurons in a brain? silicon CPU in 
a computer? ants in a colony?). Even if we were to answer the “Hard Problem”, we 
would still be faced with the fundamental question of defining the spatial bound-
ary of a conscious system (Fekete et al. 2016). For example, it is commonly said 
that consciousness arises from the brain, but clearly not all parts of the brain are 
required for consciousness (Feuillet et al. 2007). All biological systems are com-
prised of multiple complex scales of organization (Noble 2013; Laubichler et  al. 
2015) and nested within larger biophysical systems (Gilbert et al. 2012). The theo-
retical difficulty that already exists in studying measurable biological phenotypes is 
exacerbated in the scientific study of consciousness, which frames consciousness as 
a system-level phenotype which can be studied in an evolutionary (Søvik and Perry 
2016) and developmental framework. However, the only thing that researchers seem 
to agree on is that “consciousness” cannot be directly measured. In other words, 
a distinctively non-measurable trait of a biological system (level of consciousness) 
is being studied as if it were a measurable trait (e.g. wing length). In the case of 
studying consciousness as a trait within its phylogenetic context, some work deploys 
a biological epistemological pluralism (Seth et al. 2006), akin to pluralistic frame-
works for animal behavior (Kellert et al. 2006; Longino 2000, 2013; Tabery et al. 
2014). However as stated, studies of consciousness face the additional limitation 
that hidden internal states of systems (i.e. the extent of conscious awareness) are 
hidden, as opposed to the externally visible motor outputs of behavior (Tinbergen 
1963; Gordon 1992; Silvertown and Gordon 1989). Thus something different than 
epistemological or methodological pluralism is required to circumvent some of the 
fundamental issues facing the scientific study of consciousness.
It is an interesting and paradoxical time for the scientific study of consciousness 
in natural and designed systems. A sizeable fraction of scientists seem to ignore 
the fact that diametrically-opposing viewpoints to their own are also tenable given 
exactly the same experimental results. Other scientists implicitly or explicitly believe 
that the collection of more data will resolve the neural basis of consciousness in the 
future, despite some evidence suggesting otherwise (Jonas and Kording 2017; Over-
gaard 2017). And yet other scientists may be simply unaware that logical and coher-
ent arguments exist for consciousness in disaggregated entities such as the United 
States (Schwitzgebel 2015) and other “non-living” systems (Schwitzgebel 2018a). 
More experiments in human and animal brains will certainly be of biomedical and 
theoretical significance, but it seems that the irreconcilable heterogeneity of theories 
regarding “consciousness” may prevent any incontrovertible conclusions from being 
empirically reached by new experiments.
What seems to be needed is a novel and integrative approach to reconcile appar-
ent axiomatic differences among scientific theories of consciousness. As social 
insect researchers, the authors noticed that social insect colonies are often thrown 
about as exemplars of the kind of disaggregated system that cannot have conscious-
ness (e.g. a priori excluded from consideration), yet also referenced by lay persons 
as examples of higher-order “hive mind”-type consciousness. Both ends of this

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discourse (colonies are certainly not conscious, colonies are certainly conscious) are 
alien to the field of social insect behavior studies, yet commonly found in popular 
media (Decker 2013; Lasseter and Stanton 1998; Marvel 2015). Behavioral ecologi-
cal research in the social insects addresses collective outcomes at the level of the 
colony via non-metaphysical means. Philosophically, the existence of such a stark 
bifurcation in the perception of ant colonies seems to require resolution, or clarifica-
tion via empirical results.
At visual and perceptible time scales, a social insect colony exhibits behavior that 
is often referred to as “hive mind”-like, essentially implying a collectively conscious 
entity, in works of both science and science-fiction (Wheeler 1911; Hofstadter 1981; 
Seeley and Levien 1987; O’Sullivan 2010; Wilson 2017). Yet the field of social 
insect behavior never appeals to metaphysical accounts of colony behavior, focus-
ing on neurological and algorithmic processes by which collective outcomes occur 
(Gordon 2014; Theraulaz 2014; Friedman and Gordon 2016; Feinerman and Kor-
man 2017), as well as the psychological processes by which humans observe and 
define ant colony behavior (Gordon 1992). This stark contrast between the scientific 
realism of social insect ethological studies and less-grounded perspectives outside 
of the field motivates us to inject empirical information about social insect colony 
behavior back into the scientific discussion of consciousness. Our goal is not to sup-
port or deny the existence of consciousness in colonies—we remain agnostic on the 
issue here. Rather we use the ant colony as a test to explore whether the current con-
tenders for a scientific theory of consciousness are providing us with consistent and 
useful information about the world.
1.2  Forward tests and reverse tests
To help clarify the nature and utility of the Ant Colony Test for the scientific study 
of consciousness, we here discuss a dichotomy between “forward tests” and “reverse 
tests”. A “forward test” is the state of scientific operation that begins with a vali-
dated tool and goes into the world to explore a diversity of objects (Fig. 1a). This 
is normal science in the Kuhnian sense (Bird 2013; Matthes et al. 2017). A forward 
test is the usual (post-calibration) mode of operation for e.g. meter sticks or scales. 
In the normal operating mode, a forward test is used uncritically to accumulate new 
data within the previously-established paradigm (measuring the height or weight of 
objects, for example). A forward test might be considered to be the first data-col-
lecting step in performing scientific induction (generalizing theory from empirical 
observations). In contrast, a “reverse test” is when a diversity of objects are brought 
to bear on a test for the purpose of tool calibration or assessment of internal/exter-
nal coherence (Fig. 1b). A reverse test might be considered part of the deductive 
process, since it begins with theories about the world (e.g. objects don’t change in 
height or mass between sequential weighings), and then compares these theory-
driven assumptions to empirical observations. This is revolutionary science in the 
Kuhnian sense, when the tools and methodology of a paradigm are challenged in a 
manner that can retroactively change the interpretation of previous results.

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Operation of a forward test can reveal the need for a reverse test. To give a low-
level example: if a trusted scale is used for repeated weighings of the same object 
and gives different results, the scale is no longer trusted. Then the mode of operation 
transitions from forward testing (trusted scale, unknown object weight) to reverse test-
ing (unknown reliability of scale, requires objects of known weight to calibrate). At a 
higher level, a forward test can be a theoretical criterion rather than a measure of some 
physical trait. The presence of anomaly and need for reverse testing at a lower level can 
percolate through organizational or conceptual hierarchies to induce a fractal paradigm 
shift (Sihn 1997).
A forward test for consciousness would look like a metric that could be used to 
determine the conscious state of an arbitrary system (Fig. 1c), such as the presence 
of language, or a brain, or self-reflexive behavior. Indeed, the holy grail for the sci-
entific study of consciousness would be a robust forward test for consciousness in the 
universe. However, no such forward test exists, even one that could answer a simple 
binary “is this system conscious or not” (Schwitzgebel 2018a, b), let alone anything 
more nuanced (Moor 2012; Bayne et al. 2016; Van Gulick 2018).
Fig. 1   a Forward tests and b reverse tests, shown here in the context of a scale that determines the weight 
of a block. c A forward test for consciousness would be akin to a “scale” for determining the amount or 
type of consciousness of an arbitrary system. In all images, gray objects are trusted or assumed to be 
known, while red objects have unknown reliability or aspects

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1.3  The Ant Colony Test (ACT)
Here, we examine a range of theories of consciousness through the lens of what we 
have dubbed the “Ant Colony Test” (ACT), i.e. does the theory predict or allow for 
consciousness in ant colonies? The ACT is thus a reverse test for theories of con-
sciousness. As a reverse test, the function of the ACT is to ascertain the internal and 
external coherence of forward test-like theories of consciousness—for example, the 
notion that a brain, or language ability, or empathy, are necessary or sufficient for 
conscious awareness.
The ACT is not simply a thought experiment (Gedanken), though pure thought 
experiments have been tremendously influential in the study of conscious systems 
(Turing test, Searle’s “Chinese Room”, Brain in a vat, etc.). Rather, with ant colo-
nies, we can perform experiments that are informative and tractable. Unlike brains, 
social insect colonies can be ethically manipulated (Gordon 1989), divided (Win-
ston et al. 1990), or drugged (Friedman et al. 2018). Additionally, the tremendous 
evolutionary and ecological diversity of ant colonies (Ward 2014) provides research-
ers with natural experiments with which to explore various hypotheses.
2  The ACT and several frameworks for consciousness
Here we apply the Ant Colony Test (ACT) to various scientific frameworks for 
consciousness. As discussed above, contemporary theoretical frameworks for con-
sciousness amount to “forward tests”, since they each focus on a specific suite of 
salient aspects of a system, such as neuronal connectivity, that are casual or diag-
nostic of system consciousness. We focus on four genres of forwards tests for con-
sciousness, coming from four distinct fields. First we consider Neurobiological 
frameworks for consciousness of two types: structural models that focus on micro- 
or macro-histology, and functionalist models that emphasize dynamical aspects 
of brain function. Second, within a behaviorist framework we consider the trait of 
egocentric spatial awareness specifically. Third, we consider cognitive frameworks 
for consciousness, such as models that emphasize the role of emotional states or 
cognitive biases. Lastly, we consider mathematical frameworks that controversially 
formalize “consciousness” as (proxied by) something quantifiable about a system. 
Two kinds of mathematical frameworks are presented, either dealing with decision-
making and long-term planning, or with information-theoretic calculations. For each 
of these four kinds of frameworks for consciousness we juxtapose the ACT against 
their forward tests, and evaluate what insights can be gleaned.
2.1  Neurobiological frameworks
Neuroscience Diverse contemporary authors conclude that neuroscience either sup-
ports (Dawkins 2012; Fabbro et al. 2015; Barron and Klein 2016; Mashour 2018) 
or denies (Dennett 1996, 2017; Sapolsky 2017) the existence of consciousness in

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humans and other brainy organisms. While some neuroscientists (and an eager sci-
ence media) herald the unstoppable power of basic brain research to unlock the 
secrets of consciousness (Koch 2014; Koch et al. 2016), other researchers consider 
this question to be nothing more than the last evaporating vestiges of vitalism in 
biology. For example, Professor Robert Sapolsky memorably claimed that “If free 
will lurks in those interstices [of the brain yet unexplored by neuroscience], those 
crawl spaces are certainly shrinking” (Sapolsky 2004). Yet for those who constrain 
consciousness to only occur in brains, the “hard problem” falls squarely within the 
scope of neuroscience. In this case, the task is to identify the brain region (Crick and 
Koch 2005) or dynamic states (Calabrò et al. 2015; Tsuchiya et al. 2015; Mashour 
2018) associated with consciousness—a challenging and unfinished project (Kur-
then et al. 1998). We consider here forward tests for a neuroscientific basis of con-
sciousness that rely on either structural or functional findings from neuroscience.
Structural neuroscience Structural neuroscientific frameworks focus on the ana-
tomical correlates of consciousness, such as brain regional anatomy at a gross scale 
(Crick and Koch 2005), or neural circuit microarchitecture at the histological scale 
(De Sousa 2013; Grossberg 2017; Key and Brown 2018; Lacalli 2018). The ACT 
has little to say about such neuroanatomical theories: since an ant colony is not liter-
ally a brain (despite salient similarities, Hofstadter 1981), there is no possibility of 
consciousness in an ant colony according to any neuroanatomical theory. Neuroana-
tomical theories are, unsurprisingly, neurochauvinist (Walter 2009) and thus a priori 
exclude other interesting systems from scientific consideration (Baluška and Levin 
2016; Dehaene et al. 2017). The ACT suggests that theories of consciousness merely 
implicating human brain regions or aspects of cellular anatomy (such as anything 
related to the quantum brain, Hameroff 2012; Hameroff and Penrose 2014) will have 
limited carryover into other species, and even less carryover into systems with radi-
cally different architectures (e.g. computers, Turing 1950; or nations, Schwitzgebel 
2015).
Functional neuroscience Functionalist neuroscientific frameworks are worthy 
of more in-depth discussion in the context of the ACT. Functionalist frameworks 
abstract away from specific molecular details and brain regions to focus on the 
dynamical properties that might underlie conscious experience (Ross and Spurrett 
2004; Shoemaker 1993), such as self-reference (Hofstadter 2007), recurrence 
(Barron and Klein 2016), and global binding patterns of neural activity (Crick 
and Koch 1990; Singer 1999; Uhlhaas et al. 2009). Dynamic brain imaging stud-
ies use technologies such as electroencephalogram (EEG) or functional magnetic 
resonance imaging (fMRI) in humans to study the plausible neural correlates of 
consciousness (Calabrò et al. 2015; Koch et al. 2016; Tsuchiya et al. 2015). It is 
beyond the scope of this work to discuss the specific brain regions and statistical 
patterns that have been implicated in conscious awareness. We merely indicate 
that rigorous consideration of the available evidence by disciplinary experts does 
not appear to yield any unambiguous conclusions (Mashour 2018), or even sup-
port the notion that brain imaging is indeed the correct means to study conscious-
ness in humans. What is important to note is that all brain imaging paradigms 
agree that the neural correlates of consciousness change through time and can 
be proxied by dynamic observables of brain function. Or in other words, these

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neuroscientific forwards tests of consciousness believe that simple synaptic con-
nectivity patterns are insufficient to give rise to consciousness: a dead brain in a 
freezer has the same synaptic connections as a living brain, yet is unresponsive 
and probably unconscious. Apparently something more than mere synaptic con-
nectivity, something dynamic, is required to generate even the illusion of con-
sciousness (Dennett 2001; Mangan 1993). The focus on neural dynamics arising 
from static connectivity patterns motivates the search for oscillatory processes 
occurring on the timeframe at which events become consciously aware to normal 
people: on the order of hundreds of milliseconds, as opposed to nanoseconds or 
hours. A classic example is an emphasis on rapid gamma-band neural synchrony 
as a proxy of awareness (Doesburg et al. 2009). However despite some correla-
tions between neural binding patterns and aspects of consciousness in humans, it 
is not clear exactly how correlated firing rates of neurons might lead to phenom-
enological awareness (Chalmers 1996; LaRock 2006), which is a primary reason 
why functionalist neuroscientific theories of consciousness are mired in contro-
versy over even the most basic questions in the field (Calabrò et al. 2015; Koch 
et al. 2016; Mashour 2018; Tsuchiya et al. 2015).
ACT meets functionalism The ACT as a reverse test can clarify some of the 
assumptions and implications of functionalist neuroscientific theories of con-
sciousness. There is a large literature on synchronized collective rhythms in 
social insect colonies, where collective rhythms occur over time scales ranging 
from seconds to annual seasons (Bochynek et al. 2017; Cole 1991; Gordon 1983; 
Hayashi et  al. 2012; Phillips et  al. 2017; Richardson et  al. 2017). Like neural 
rhythms, these oscillations in colony collective behavior are an emergent outcome 
of interactions among system subunits (Hofstadter 1981). Indeed, the dynamics 
of transient ensembles of neurons and task groups of ant workers show qualita-
tive and quantitative similarities (Hofstadter 1981; Davidson et al. 2016). In both 
the brain and ant colony setting, higher-order outcomes are shaped by evolution 
to optimize the adaptive response to ecologically-important stimuli (Constant 
et al. 2018; Gordon 2014), as the case with brain dynamics (Sapolsky 2017). As 
noted above, a hardline anthropocentric interpretation of the brain imaging stud-
ies would conclude that only humans, or neurologically-similar species like apes, 
are conscious, which has low generalizability, especially when considered from 
an evolutionary perspective (Mashour and Alkire 2013; Søvik and Perry 2016). 
Abstracting away from the exact neural circuitry or brain regions apparently 
involved in consciousness in humans is a move towards Functionalism, and high-
lights the role of information-integrating processes in generating human aware-
ness (Bayne and Carter 2018). Should we take this Functionalist turn, then ant 
colonies do indeed appear to exhibit multi-scale oscillatory processes that could 
be considered to be similar evidence for colony consciousness. In other words, 
if the oscillations in the brain are (a proxy for) consciousness, then similar but 
slower processes in ant colonies could be considered as the basis of (a proxy for) 
consciousness as well. For those who think that such multi-scale oscillations are 
not even proxies for consciousness in ant colonies, they must additionally explain 
why we can take similar neural oscillations to be causal or correlative of human 
consciousness (Crick and Koch 1990; Doesburg et al. 2009; Schmidt et al. 2018).

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2.2  Spatial sense
Spatial awareness and organismal consciousness In two articles Barron and Klein 
(Barron and Klein 2016; Klein and Barron 2016) (henceforth B&K and K&B) set 
forth a framework for subjective experience in animals organized around the concept 
of a spatial sense. There they convincingly argue that an “integrated and egocentric 
representation of the world from the animal’s perspective is sufficient for subjective 
experience” (Barron and Klein 2016, p. 4900). The philosophical argument behind 
this is that if an organism has an internal model of how the world is supposed to 
behave in response to its motion, the discrepancy between the expected output of 
the model and the actual input from the organism’s sensory systems is sufficient 
for the organism to have a subjective experience of its own movement through the 
world. This basal system, with subjective experience built into it, has then through 
evolution been coadapted into more elaborate forms of subjective experience and 
is at the center of animal sentience. B&K go onto show how the neurobiological 
systems in the mammalian brain (Barron and Klein 2016; Klein and Barron 2016) 
are organized to enable a spatial sense like the one imagined above. It is precisely 
the kinds of neural circuits involved in this ability that are believed to be necessary 
for consciousness in humans (although some disagree; Hill 2016; Key 2016; Mallatt 
and Feinberg 2016). They then carefully establish a model for spatial processing in 
insect brains that aligns with what is currently know about the mammalian system, 
and argue that this can be taken for evidence of subjective experience in insects also 
(Barron and Klein 2016; Klein and Barron 2016).
B&K never state specifically that their theory of animal experience is a forward 
test of consciousness, yet in both of their articles they implicitly use it as such (Bar-
ron and Klein 2016; Klein and Barron 2016), e.g. “One of the virtues of the account 
we have endorsed is that it also gives an evidence-based argument for where to draw 
the line between the haves and have-nots” (Barron and Klein 2016, p. 4905). In 
addition, since their publication, several other authors have expanded their line of 
logic to argue for sentience in a wide range of other animal organisms (Shanahan 
2016; Søvik and Perry 2016). It goes without saying that the arguments that B&K 
build roughly equate to a forward test for sentience in insects—it is the whole point 
of their argument (Barron and Klein 2016). But in the original paper they go on 
to speculate as to where one might find consciousness beyond insects. They deny 
consciousness to cube jellyfish on the grounds that the nervous system is entirely 
decentralized, so there is nowhere for spatial information to be integrated (Barron 
and Klein 2016), and this argument is presented much in the same manner in the 
second article (Klein and Barron 2016). Further, nematodes are not considered sen-
tient either. K&B acknowledge the centralized nervous system of nematodes, but 
argue that there is nothing in their behavior that suggests that they have any aware-
ness of their surroundings, e.g. they do not hunt for known objects in their envi-
ronment, rather they respond to immediate stimuli around them (though this is not 
strictly true; Hendricks 2015; Shtonda and Avery 2006; Sokolowski 2010; Stern 
et al. 2017).
In the second article K&B again revisit the nematode and take the argument 
slightly further: They acknowledge that many different types of information are

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integrated simultaneously in the nematodes nervous system, but as there is no con-
cept of space, no subjective experience can exist (Klein and Barron 2016). In both 
papers B&K open the door slightly for sentient crustaceans, based on the similar-
ity of nervous systems between crustaceans and insects (not surprisingly, given that 
both are arthropods). Other authors have used B&K’s line of reasoning to argue for 
sentience in cephalopods and more basal invertebrates (Mather and Carere 2016; 
Søvik and Perry 2016). Like all theories of sentience, there are many that disagree 
with the arguments made by B&K, but it is clear that it is a theory that makes very 
specific predictions about what is required for sentience to exist and evolve, and as 
such we predict many will use it as an attempt at a forward test of consciousness in 
the years to come.
What would happen if we apply the ACT to the criteria of K&B? That is, apply 
the criteria of K&B to a colony of ants. This is a very different question from apply-
ing the criteria to an individual ant. Individual ants, like bees, do have a spatial sense, 
and as insects contain all the brain structures and circuitry pertinent to B&K’s argu-
ment (Fleischmann et al. 2018; Kim and Dickinson 2017; Wehner 2003). So we sus-
pect that K&B would claim that an ant worker has a similar level of consciousness 
to a bee worker. To apply this theory at the colony level, the question we must ask 
is whether or not the colony, as a whole, has a spatial sense. It is tempting to dismiss 
this as a nonsense question out of hand—how can a whole colony of anything have 
a sense of its environment? But to dismiss the question without further investigation 
would be akin to a priori dismissing the spatial sense of a human or a single ant. After 
all, brains are simply made up of a bunch of individual neurons, so how can the entire 
organism have a sense of anything either? This is where the reverse test properties of 
the ACT start to emerge. Does the substance matter, e.g. neurons versus ants, or is it 
the processing of information that allows the spatial sense to exist that is the important 
factor for the model? It is hard to see anything from what B&K writes that would limit 
the described spatial sense to systems that process information with neurons. It just so 
happens that two independent systems (vertebrates and insects) have evolved the same 
solution to similar spatial navigation problem using neurons, though other systems 
might find non-neuronal solutions. Does the ant colony display the kind of spatial sense 
described by B&K as required for consciousness? Tentatively, it is tempting to say yes. 
Colonies behave as if they have awareness of their surrounding area: they exploit spa-
tial resources in an efficient manner (Gordon 1995; Portha et al. 2002; Adler and Gor-
don 2003; Flanagan et al. 2013; Robinson 2014). Does the colony suffer from the same 
problem as the jellyfish? That is, is there a lack of integration of information? Given 
that the regulation of colony resource exploitation is a collective process in which no 
ant necessarily “knows” the entire outcome, it would be hard to argue that information 
about space is not integrated at the colony level. B&K present a further requirement 
that is more applicable to the ant colony: not only does there need to be integration of 
information, but the information integration must be centralized. How could informa-
tion processing be centralized in a colony? Perhaps one could imagine that all the infor-
mation would have to be integrated in one or a few ants (e.g. these central ants would 
somehow possess all the vital information for spatial processing—either individually or 
somehow shared amongst them). How does this compare to the situation in the nerv-
ous system? Do we imagine that one or a small number of neurons is where spatial

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information is integrated? Are those few neurons then the “seat” of subjective experi-
ence, or is their mere presence in a nervous system sufficient for more remote neurons 
to take part in the sea of experience? One could imagine that the lack of centralization 
could be used to argue why (current) computers cannot be said to be conscious, even 
if behaviorally they appear to process spatial information in accordance with K&B. 
While information is integrated in a computer, it does not occur in any centralized way 
(i.e. all transistors are equally important, none have privileged information others do 
not have, and the information is fully distributed). Further discussion of informational 
integration from the perspective of Integrated Information Theory is in a later section.
Further supporting the idea that ant colonies possess spatial awareness is that ant 
colonies are fooled by spatial illusions (Sakiyama and Gunji 2013, 2016), much in the 
same was a humans are fooled by visual illusion (Alexander 2017; Brancucci et al. 
2011; Guterstam et al. 2015; Pereboom 2016). The human neurological response to 
a sensory illusion is taken by some as evidence that a change in conscious experience 
is occurring (Brancucci et al. 2011; Guterstam et al. 2015; Pereboom 2016; Alexander 
2017). So should we then assume that the susceptibility of an ant colony to a spatial 
illusion can also be taken as evidence for a conscious experience at the colony level? 
Again one might claim that in an ant colony there is no central integration of informa-
tion, hence no awareness of the illusion. However only a small fraction of neurons in 
the brain might be involved in processing visual impulses amplified by sensory cells. 
Yet all cells of the human are affected by the activity of just these few. It would not 
make sense to say that any skin cell or single neuron “fell for an illusion”. Similarly it 
does not make sense to say that any single worker was fooled, the illusion occurred via 
a colony-level process. Thus we cannot explain away the susceptibility of the colony 
to illusion by reductionistically appealing to individual worker behavior. The outcome 
of being fooled arises as a system property, in both humans and ant colonies (Baluška 
and Levin 2016). The spatially-organizing activity of colonies occurs as a consequence 
of interactions among individuals, most of which might not be directly involved in the 
organizational task. For example, the work of a small fraction of trash-worker nest-
mates can alter the distribution of colony waste, leading all other workers to alter their 
behavior through the process of stigmergy (Gordon and Mehdiabadi 1999; Theraulaz 
and Bonabeau 1999; Theraulaz 2014).
So after putting K&B through the ACT we have seen that there is one issue that 
needs to be clarified before K&B can be a more useful forward test. It is not clear what 
it is about centralization that makes it necessary, nor what it means for information 
processing to be centralized. Integrating information centrally does not, as far as we can 
think, alter the behavioural output in any way.
2.3  Cognitive frameworks
2.3.1  Emotional experience
It is perhaps not a coincidence that when people paraphrase Thomas Nagel’s now 
famous statement “An organism has conscious mental states if and only if there 
is something that it is like to be that organism—something that it is like for the

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organism to be itself.” (Nagel 1974), it is common to replace “something that it is 
like”, with “feels like something” to be a particular organism. That turn of phrase, 
which introduces the concept of “feeling”, is immediately understandable, though 
perhaps tautological—to assume it “feels like” anything at all is to already pre-
sume that the system in question is having some sort of conscious feeling experi-
ence. Thus arguments for consciousness by appeals to emotion appear unable to 
rigorously resolve scientific questions about consciousness, since they are essen-
tially pre-loaded by the thinker’s axioms to result in whatever conclusions are 
desired (consistent with their value system). Despite this seeming logical weak-
ness, the ability to feel is by many considered a key, if not the key, characteristic 
of consciousness (Damasio 2000; Panksepp 2004, 2011). From an animal wel-
fare perspective, this trait has often been used as the defining feature that should 
be used when considering what rights animals should be granted (Dennett 1995; 
Singer 1975). Like all phenomena related to sentience, emotions are not directly 
measurable. By their very definitions, emotional qualia are private experiences 
to the subjects having them. This does of course make it difficult to assess the 
emotional state of individuals that cannot self-report what they are feeling, i.e. all 
beings except communicatively-capable humans. In order to circumvent this inhi-
bition, the field of affective neuroscience has inferred feelings in non-human spe-
cies by studying neural correlates of human emotions, so called affective states 
(Fabbro et al. 2015; Panksepp 2011). This research paradigm has been very use-
ful as a wedge for proponents of animal welfare, culminating in the Cambridge 
declaration on consciousness (Allen and Trestman 2017; Low et al. 2012). The 
ability of animals to feel pain or suffer has since then been included in the legisla-
tion of many countries (e.g. all member countries of the European Union, Euro-
pean Commission 2016).
Cognitive bias as a forward test for the ability to feel Because it is not always 
tractable to study the neural response of animals directly and because the nervous 
systems of some animals differ fundamentally from humans in terms of structure, 
indicators for inferring affective states behaviorally across systems have been devel-
oped, such as mirror tests (Newen and Vogeley 2003; Toda and Platt 2015) or behav-
ioral paradigms involving gambling with ambiguous stimuli (Perry et al. 2016). The 
most commonly used indicator here is the appearance of so-called “cognitive bias”. 
In cognitive bias paradigms, animals are trained to learn that one cue (or range of 
cues) is associated with a reward while another cue (or range of cues) is associated 
with something aversive. The animal is then given a treatment that is supposed to 
affect its emotional state, e.g. something that is meant to make the animal feel anx-
ious, before being presented with an ambiguous cue that is intermediate between the 
cues (or range of cues) that has previously been associated with reward or punish-
ment. In these experiments a change in behavior, such as being more reluctant to 
approach the ambiguous cue following the anxiety-inducing treatment, is interpreted 
as evidence that an emotional state has biased the cognitive decision of the animal 
(Mendl et al. 2009). Performing cognitive bias tests allows researchers to easily infer 
both positive and negative emotional states in all sorts of animals. This has been 
used to infer the presence of emotional states in a wide range of vertebrates (Bethell 
2015). The cognitive bias paradigm has also been used to infer negative emotions in

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honey bees (Perry et al. 2016) and crayfish (Fossat et al. 2014), and more recently 
positive emotions in bumble bees (Alem et al. 2016).
Some have argued that it makes no sense to infer emotions in invertebrates on the 
basis of cognitive bias (Giurfa 2013), on the ground that simpler mechanisms, i.e. 
cognition without sentience, could explain the behavior. There seems to be no good 
argument for thinking that cognitive bias experiments allow us to infer emotional 
states in mammals, but not other animals. So far, every study on this phenomena in 
invertebrates has also included evidence that similar neurochemicals are involved in 
causing the emotional states as in mammals (Barron et al. 2010).
Putting cognitive bias through the ACT​ No one has explicitly tried cognitive 
bias experiments with a colony of ants. In theory such experiments are completely 
possible. Colonies do regulate their foraging based on external cues (Cooper et al. 
1985; Núñez and Giurfa 1996) and modulate their behavioral response to external 
perturbations (Gordon 1986; Gordon et al. 1992). One can therefore imagine a setup 
where a colony learns to forage more in response to one cue, and reduce its forag-
ing intensity in response to another cue. How would we interpret the result if the 
colony displayed a bias in its response to an ambiguous cue, after some treatment? 
The treatment could be pharmacological, such as dopamine (Friedman et al. 2018), 
a dopamine antagonist (Perry et al. 2016), or an opiate (Entler et al. 2016), or eco-
logical (such as an increase in humidity or ambient light), and would be meant to 
shift the emotional state of the colony in a positive or negative direction. One could 
claim that in a such a situation, the experimenter is merely drugging individual ants, 
not the entire colony. In this case, should we consider caffeine to only be influencing 
individual neurons, rather than humans as individuals? When a human takes a drug 
that “alters their level of consciousness”, only a small fraction of their cells (e.g. 
neurons expressing a certain type of receptor) might be directly affected. However, 
the whole body’s behavior might be altered by the change in function of the few cells 
(not unlike the case with the visual illusions). By the same logic, if drugging a small 
fraction of workers leads to altered behavior of the colony, such a treatment would 
be as “consciousness-altering” as the case in humans. It is possible to imagine that 
shaking the whole colony would put it in an agitated or pessimistic state, causing it 
to forage less in response to an ambiguous cue, as well as display short term panic 
behaviors followed by medium-long term coping behavior. Immediately it is tempt-
ing to think that it would tell us nothing about the emotional state of the colony. 
But how is this criticism different from that levied against single honey bees? The 
rejection of cognitive bias at the colony level, perhaps by reductionistically localiz-
ing causality solely in changes in individual worker brains, would be akin to reduc-
ing organismal learning solely to some subset of neural changes. One might claim 
that colonies are performing cognition (computation) at a sufficient organismal-level 
complexity for consciousness, but these behaviors are simply not accompanied by 
qualia. Perhaps Daniel Dennett would call such a system a “p-zombie colony”. How 
would we ever be able to differentiate p-zombie colonies from qualia-laden, con-
scious colonies? In other words, if one rejects conscious experience at the colony 
level despite the appearance of cognitive bias in experiments, then they also lose 
grounding for analogous cognitive bias-based experiments regarding emotional 
experience in a range of species. In a paper that considers pessimistic honey bees,

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Bateson et al. state that “[i]t is logically inconsistent to claim that the presence of 
pessimistic cognitive biases should be taken as confirmation that dogs or rats are 
anxious but to deny the same conclusion in the case of honeybees” (Bateson et al. 
2011). If in fact a case for conscious honey bees can be made (Barron and Klein 
2016), then what would prevent us from saying that it is equally inconsistent to not 
apply the same standard to an ant colony?
2.4  Mathematical frameworks
The logic in the previous behavioral and neurobiological sections is built around 
the fundamental assumption that it is biological creatures that are the only systems 
that are plausibly conscious. There is somewhat of a bio- or neuro-chauvinism in 
the suggestion that only (certain) biological systems can exhibit self-awareness, yet 
such strong claims are rarely specified or directly supported in such research. Teth-
ering theories of consciousness to biological systems implicitly comes with the axi-
omatic baggage of having to explain why non-neural or non-biological systems are 
unable to be conscious. Mathematical theories of consciousness tend to emphasize 
abstract informational and causal aspects of system function rather than biological 
idiosyncrasies such as cytoskeletal architecture or brain regional activity. This math-
ematical abstraction ideally results in a numbered or graded scale that quantifies the 
extent or type of consciousness in a system. The appeal of a numerical value that 
“measures” consciousness is undeniable to some and unthinkable to others. How-
ever, the benefits of such formal frameworks are clear in comparison to boutique 
theories that only apply to humans or neural systems. First, numerical accounts of 
consciousness may allow objectively better-informed medical and ethical decision-
making in humans, for example by quantitatively resolving questions about the 
experiential awareness of e.g. pre-birth humans or those in a coma. Second, math-
ematical abstractions might provide a less-biased metric for measuring the extent of 
consciousness in other biological systems, so that consciousness might be studied in 
a truly phylogenetic framework (Mashour and Alkire 2013; Barron and Klein 2016; 
Søvik and Perry 2016). Third, it might allow meaningful quantification of the level 
of consciousness in unconventional systems such as “artificially intelligent” com-
puters (Moor 2012) or countries (Schwitzgebel 2015). Generally, these Mathemati-
cal theories formalize some quantitative proxy of a system’s conscious capacity via 
appealing to the internal causal power or capacity for informational integration of 
static or dynamical aspects of the system.
First we consider Integrated Information Theory (IIT) as a forward test for con-
sciousness, then reflect what the ACT as a reverse test reveals about IIT and prob-
ably other theories of consciousness based upon the topological (Bayne and Carter 
2018) or geometric (Fekete et al. 2016) integration of information. IIT is a math-
ematical theory of consciousness that is to be commended for its intellectual bold-
ness (Bayne et al. 2016; Tononi et al. 2016; Tononi and Koch 2015), though it is not 
without critique (Bayne 2018; Schwitzgebel 2018b). IIT takes an opposite approach 
to consciousness than many other scientific theories. Rather than focusing on the 
commonalities of biological systems that are agreed to be conscious and then using

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inductive logic to explain how consciousness appears in these systems, IIT begins 
with 5 axioms (basic, unjustified statements) about consciousness, then deduces 
conclusions about which systems might have what amount of consciousness. The 
quantity of consciousness in a system is measured with a single number reflecting 
the system’s ability to irreducibly integrate information, denoted with the character 
Φ. IIT predicts that systems with larger values of Φ are more conscious, though it 
should be added that Φ calculations do not exist for any real biological systems so it 
is not clear what specific values would mean. This definition leads to some unintui-
tive conclusions about which systems are conscious (Aaronson 2014), though this 
may be a general feature of all frameworks that attempt to quantify consciousness 
(Schwitzgebel 2018a). IIT predicts that consciousness occurs at a maximum Φ value 
among all possible spatial and temporal partitionings of the system, denoted as Φmax. 
IIT predicts that the subsystem with the highest Φmax is the one at which conscious-
ness occurs at. Information integration certainly occurs within the brain of an ant 
or bee worker, which is the basis for the claims of minimal self-awareness in indi-
vidual workers by B&K (Barron and Klein 2016). However, truly emergent forms of 
cognition arise at the level of the colony (Marshall et al. 2009; Feinerman and Kor-
man 2017), enabled by the patterns of information transfer among workers (Gordon 
2010). The appearance of irreducible informational processes at the colony level 
seems to support a non-trivial increase in Φ from aggregates of separated workers 
compared to an integrated colony, suggesting that Φmax is occurring at the colony 
level. While it is too early to make claims about IIT demonstrating consciousness at 
the level of an ant colony, it does seem that the colony will have a Φmax higher than 
that of aggregate individual workers, and thus represent a conscious entity.
Second, we consider the The Free Energy Principle (FEP) as a forward test 
for consciousness in dynamical systems, then reflect on how the ACT serves as a 
reverse test for FEP. Specifically we discuss FEP in the context of long-term plan-
ning as an attribute of conscious systems, an idea framed in less-quantitative ways 
by other sources (Proverbs 6:6–8). Based upon the physical evolution of physi-
cal systems, FEP is a far-reaching framework that considers biological systems as 
dynamic multilevel processes that fundamentally perform statistical inference on 
themselves and their environment (Friston 2012, 2017a; Kirchhoff et al. 2018; Ram-
stead et al. 2017). Successful system persistence is equivalent to, and underlain by, 
the act of self-evidencing (Friston 2018). The persistence of any dissipative system 
amidst the chaos and struggle of our entropic world directly implies an adequate 
generative model of the system’s ecological context (Constant et  al. 2018). FEP 
has implications in many physical and biological domains, though here we concern 
ourselves mainly with what FEP says about conscious and self-aware systems. As 
a system’s “temporal thickness” (ability to perform successful inference over long 
time scales) increases, FEP says that a system becomes increasingly sentient (Fris-
ton 2017b, 2018; Friston et al. 2018). Ant colonies certainly appear to plan for the 
future amidst uncertainty (Crompton 1954; Hölldobler and Wilson 1990; Hasegawa 
et al. 2016). Simply put, the ability of the ant colony to perform long-term (e.g. 
multi-month/year) planning amidst stochastic environmental conditions is crucial 
for colony survival and fitness (Gordon 2013). This suggests that effective temporal 
models at the colony level are shaped by natural selection over millions of years in

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the > 14,000 extant ant species, consistent with FEP’s phrasing of consciousness as a 
natural process of multilevel inference (Friston 2017b). Because of the deep tempo-
ral colony-level models that allow long-term planning of ant colony behavior, FEP 
would appropriately consider the ant colony a true “self”.
According to recent contributions, self-awareness goes beyond mere temporal 
thickness in two important and related ways (Friston 2018; Friston et al. 2018). The 
first key addition that self-awareness requires beyond temporal thickness is the abil-
ity to generate and entertain counterfactual scenarios, then the ability to test these 
counterfactuals using active inference (Bruineberg et al. 2016). For example while 
reading, you might imagine that this sentence could have been written differently 
(which makes you conscious according to FEP), while an automated text-scraping 
program would read the sentence without considering alternatives (and hence is not 
conscious). In an interview, Dr. Karl Friston notes that the ant colony performs long-
term planning, but that it is not clear whether the ant colony entertains counterfactu-
als (Friston et al. 2018). Perhaps an example of a colony-level counterfactual occur 
when the dynamic interaction network of the colony (Gordon 2010) simulates the 
state in which the colony is hungrier than  it is, e.g. to stimulate foraging (John-
son and Linksvayer 2010). The second prerequisite of FEP for conscious awareness, 
beyond the appearance of long-term planning via counterfactuals, is an internal 
model that differentiates self-caused events from events beyond the causal reach of 
the system. For biological systems that engage with an environment rich in similar 
agents (e.g. humans interacting with humans, Friston 2018; or worms interacting 
with worms, Friston et al. 2018), entertaining long-term generative models of the 
environment entails parsing out the causal influence of one’s self from other similar 
selves. It is the case that ant colonies are often interacting with other ant colonies 
nearby, of the same or different species (Adler et al. 2018). The interactions among 
conspecific colonies are crucial for ecological success since neighboring colonies 
are in direct competition, and colonies update their behavior over the timescale of 
days and years to adjust to the presence of nearby colonies (Gordon 1995; Adler and 
Gordon 2003). Thus it does seem to be the case that ant colonies have thick tem-
poral models of their environment, probably including the influence of conspecific 
neighbors and with an ability to differentiate between causes under the control of the 
colony from causes that are not within the colony’s control. In summary, FEP might 
support the notion of a rudimentary self-awareness or genuine self-consciousness 
for ant colonies, due to their ability to perform long-term planning, possibly enter-
tain counterfactuals, and maintain a collective model of self- vs. non-self. However 
few experiments have been performed to investigate counterfactuals or colony-level 
temporal models in the social insects, so more work is required.
3  Overview of the “Ant Colony Test” across disciplines
We presented the ACT as a reverse test for theories of consciousness. The ACT has 
advantages over other thought experiments for theories of consciousness (Turing 
1950; Moor 2012; Cole 2014; Fekete et al. 2016) in that ant colonies have a large 
amount of empirical work previously done in the system, and there are growing

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possibilities for further neurobehavioral experiments to test theories of conscious-
ness (Alem et al. 2016; Perry et al. 2016). Thus the ant colony is a useful model 
system for future philosophical and scientific work on consciousness. Colonies are 
embedded within nests that exist within ecosystems, just like brains are embedded 
within bodies that exist within ecosystems. Thus ant colonies, like human organ-
isms, represent encultured extended phenotypes that perform extensive niche con-
struction. Also like brains, colonies plus their built environments are the unit of 
selection and bearer of fitness (Wheeler 1911; Linksvayer 2015; Boomsma and 
Gawne 2017). Thus from the ecological and evolutionary perspectives, it stands to 
reason that emergent self-reflexive dynamics might arise at the scale of the entire 
colony (beyond even that of the worker) for the same reason that such dynamics 
have been selected for in organisms such as humans.
Though neuro-centric frameworks for consciousness a priori exclude ant colonies 
from possessing consciousness, multiple other frameworks discussed above do pre-
dict that awareness might occur at the level of the colony. We are then left to either 
accept the claim that colonies of ants are phenomenologically-aware entities, or to 
acknowledge that current approaches to investigating consciousness scientifically 
are individually inadequate and collectively inconsistent. This unresolved bifurca-
tion implies that while current disciplinary approaches to the study of consciousness 
may provide fascinating insights into the physiology of the brain and the statistics 
of information processing by cognitive systems, they may be unable to answer fun-
damental questions about the nature of consciousness. While we do not dispute the 
soundness of the scientific investigations conducted by most consciousness research-
ers, we hold that measurable proxies of consciousness are limited or ambiguous at 
best, and misleading at worst.
As a consequence, we welcome the authors/followers of theories that allow for 
conscious colonies to either (1) explain why their theory is plausible if they reject 
the idea that colonies are genuinely conscious despite fulfilling the requisites of the 
theory, or (2) elaborate on the character of colony consciousness and explore how a 
disaggregated entity like a colony can give rise to a unified conscious experience.
4  Conclusion: go to the ant, thou philosopher
Humans have long been fascinated by the ineffable nature of their own conscious 
awareness, and have extended this questioning to ask whether other systems might 
have similar conscious experiences as well. Today, the interdisciplinary field of 
“consciousness studies” addresses these mysteries through a diversity of philo-
sophical, cognitive, biological, and mathematical frameworks. Sundry frameworks 
for consciousness fall under the category of what we call a “forward test”, in that 
they aim to provide a metric that could assess the level of consciousness of arbitrary 
human states or non-human systems. However, the lack of coherent theory in this 
area makes the progress research chaotic at best and confusing at worst. Really the 
hunt is on for reverse tests now: questions, experiments, and perspectives that are 
able to group or differentiate various frameworks for studying consciousness.

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In service to the challenge of developing a scientific theory of consciousness, 
we took an empirical and pluralistic approach by assessing how diverse “theo-
ries of consciousness” might assess the status of awareness in an ant colony. The 
answers were predictably unsatisfying to the question of whether a colony is or 
is not conscious, as resolving the actual phenomenological status of a colony 
was not our agenda. Instead, the use of the ACT reveals that even without defini-
tively answering whether colonies do have consciousness, a rigorous reverse test 
for theories of consciousness might be useful for the field. This work is just the 
beginning of a more formal meta-analysis of consciousness and collective behav-
ior across scales in the natural and designed worlds: the foraging trip of a thou-
sand nestmates begins with a single pheromone trail.
Acknowledgements  We thank Tucker Chambers, Zach Phillips and Dr. Clint J. Perry for their comments 
on an earlier draft.
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*Extraction method: pymupdf*
