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From false beliefs to true interactions

Are chimpanzees socially enactive?1

Sarah Vincent and Shaun Gallagher

In their 1978 paper, psychologists David Premack and Guy Woodruff posed the question, “Does the chimpanzee have a theory of mind?” They treated this question as interchangeable with the inquiry, “Does a chimpanzee make inferences about another individual, in any degree or kind?” (526). Here, we offer an alternative way of thinking about this issue, positing that while chimpanzees may not possess a theory of mind in the strict sense (to be explained shortly), we ought to think of them as enactive perceivers of practical and social affordances. As such, we reframe the question: “Are chimpanzees socially enactive?”

In the first section, we briefly review the well-known theory of mind and behavior-reading accounts. We then present a more detailed account of the enactivist approach to social cognition. In the second section, we contrast these three accounts as they apply to a number of empirical studies related to social cognition in chimpanzees (Pan troglodytes), defending an enactivist interpretation of the data.

Theory of mind, behavior-reading, and interaction theory

Theory of mind (ToM) approaches have traditionally assumed that we do not have direct access to the minds of others (Sellars 1956; Gallagher 2016).2 Accordingly, ToM claims that only some form of inference (i.e., either theoretical inference or simulation) makes possible one’s understanding (or “mindreading”) of the mental states of others.

Behavior-reading (BR) accounts offered the first alternative to ToM views. As accounts of mindreading began to emphasize its predictive purchase (i.e., with respect to behaviors), some argued that we are able to predict the behavior of others on the basis of observations about the relationship between current behavior and the environment in which the behavior occurs – without attributing mental states (Povinelli 2000; Povinelli and Vonk 2004; Penn and Povinelli 2007). According to this camp, what some take to be evidence of ToM is in fact only evidence of associative learning.

The enactivist account of social cognition, sometimes termed ‘interaction theory’ (IT), is an alternative to both ToM and BR views – an alternative, we argue, that is especially useful for making sense of social cognition among chimpanzees (and perhaps in other species more generally). Drawing on phenomenological resources, especially the work of Merleau-Ponty, IT challenges ToM’s assumption that we do not have direct access to other minds, in part by defining minds as embodied and situated. In most of our everyday encounters with others, we do not assume a spectatorial view, observing others from a third-person perspective. Rather, IT claims, mindreading by theoretical inference or simulation is a relatively rare, more specialized approach to gaining understanding of another in peculiar circumstances or when interaction and communicative processes involved in most of our everyday encounters fail. Crucially, rather than merely observing, we tend to interact with others in highly contextualized social settings, via communicative acts, or in normatively circumscribed and sometimes prescribed relations, which often support our direct enactive perception of the embodied intentions and emotions of others. Put simply, interaction theorists hold that we understand others primarily through embodied and situated instances of interaction – directly perceiving others as minded beings (Gallagher 2008, 2012). We are not primarily observers but rather participants with respect to social cognition.

IT takes social perception to be enactive (or action-oriented), involving sensory-motor skills rather than the passive reception of sensory inputs (Varela et al. 1991; Hurley 1998; Noë 2004). Generally, we perceive the world as affording action (practical affordances), and we perceive others as affording interaction (social affordances). We also perceive intentions and emotions in others’ postures, movements, gestures, facial expressions, gaze direction, vocal intonations, etc. In this regard, IT references embodied cognition research and specific conceptions of intention and emotion.

Importantly, intentions are not hidden mental states. They include bodily or motor intentions (so-called ‘M-intentions’) reflected in the kinematics of movement and action, as well as present or proximal intentions (‘P-intentions’ or intentions-in-action) where a prior intention is specified in terms of present context (Pacherie 2006, 2008; Searle 1983). That M- and P-intentions can be perceived in the other’s actions is not an a priori claim; there is good scientific evidence to support this claim. If I pick up a cup to drink from it, the shape of my grasp is different than if I pick it up to throw it (Jeannerod 1997). The intentional aspects of bodily movements are intrinsic to and reflected in the dynamic kinematics of movement (Ansuini et al. 2006, 2008; Marteniuk et al. 1987; Sartori et al. 2011). As Becchio et al. (2012) have shown experimentally, even in the absence of contextual information, these intentions can be perceptually differentiated as such in bodily movement. Indeed, this is a capacity that develops early in infancy. Seven- to nine-month-old infants can perceive certain ambiguous acts, like offering and withdrawing an object, as reflecting playful intentions, with different goals and outcomes than when the same intentions are interpreted literally (Legerstee 2005; Reddy 2008). P-intentions are closely tied to context, and there is evidence for the perception of P-intentions (as well as emotions) in studies of bodily kinematics and the dynamics of social attention and contextualized interaction in adults (Atkinson et al. 2007; Lindblom 2015).

Emotions, too, involve aspects of embodied mind. Emotions are not just internal experiences; they are complex patterns that include bodily states and expressions. If we think of emotions as “individuated in patterns of characteristic features (Newen et al. 2015: 187) – features that may include bodily expressions, behaviors, action expressions, etc. – then emotion perception can be considered a form of perceptual pattern recognition (Izard 1972; Izard et al. 2000; Newen et al. 2015). We can directly perceive a pattern of expressions and behaviors – and as such, directly perceive a sufficient amount of the pattern that constitutes the emotion. Philosophers like Scheler (1954: 260–261), Wittgenstein (1967: §229; 1980: §170, §570), and Merleau-Ponty (2012) have argued for this view.

The case for enactive cognition in chimpanzees

Which of these approaches to social cognition best fits with our present knowledge regarding nonhuman animals? At the instigation of Dennett (1978), much of the ToM theorizing about social cognition focuses on false-belief tests, regarded as the standard experimental design for assessing ToM in children (Wimmer and Perner 1983; Baron-Cohen et al. 1985; Leslie and Frith 1988; Onishi and Baillargeon 2005; Senju et al. 2011).

Call and Tomasello (1999) presented great apes (including five chimpanzees) with a nonverbal false-belief task. The experiment involved two humans (a hider [H] and a communicator [C]) and one ape. Two boxes were placed between H and the ape, with one containing food. C was able to see which box the food was placed in, but the ape was not. The ape saw C place food in a box, walk away, and turn her back to H and the ape, while H switched the location of the food. The switch was made obvious to the ape, but the ape still did not know which box the food was in. When C returned, she placed a marker (a previously trained signal to the ape about where the food was located) on the box that originally (but no longer) contained the food. None of the apes succeeded at selecting the correct box containing the food when both boxes were subsequently presented to them, which suggests that they failed to recognize the false belief of C. Call and Tomasello concluded that the apes did not have a theory of mind. They were careful to point out, however, that apes nonetheless do have sophisticated cognitive and social abilities and interact with each other in intelligent ways.

As an alternative to a false-belief task, Tomasello et al. (2003), following Hare et al. (2000), utilized food-competition experiments to assess social cognition in chimpanzees. In the original experiment, Hare et al. (2000) positioned a subordinate chimpanzee and a dominant chimpanzee in separate rooms that were linked by a shared space. In the shared space, a food item was placed in view of both chimpanzees, while additional food was placed behind a barrier that prevented the dominant chimpanzee from seeing it. The subordinate chimpanzees approached the latter food, which was not visible to the dominant chimpanzees – even when the subordinates were allowed to enter the mutual space first. Tomasello et al. analyze this behavior as follows: “Chimpanzees actually know something about the content of what others see and, at least in some situations, how this governs their behavior” (155). They then describe chimpanzees as possessing “a social-cognitive schema enabling them to go a bit below the surface and discern something of the intentional structure of behavior and how perception influences it” (156) – but (consistent with the Call and Tomasello 1999 results) not as possessing a full-blown ToM.

Povinelli and Vonk (2004), however, offered an alternative BR account. According to their analysis, chimpanzees may be able to reason only about behaviors (as opposed to construing those behaviors in terms of mental states). With respect to the Hare et al. (2000) experiment, Povinelli and Vonk suggest that a subordinate chimpanzee needs only to have two beliefs: (a) that there is no barrier between the dominant chimpanzee and the first food item, and (b) that the subordinate chimpanzee could be punished for taking that food. Here, in contrast to the ToM-based analysis, there is no need for the subordinate chimpanzee to have a third kind of belief (i.e., concerning the mental states of the dominant chimpanzee). The BR view, according to the researchers, is then a more parsimonious explanation and should be preferred.3 [For a further discussion of BR and mindreading, see Lurz, Chapter 21 in this volume.]

An enactive analysis of the Hare et al. (2000) experiment would include the idea that chimpanzees are aware of affordances in the situation. The subordinate chimpanzee can see that the dominant chimpanzee can see some things and not others (Povinelli and Eddy 1997). The affordances are not only physical, in terms of whether the chimpanzee is able to reach and grab the food, for example; they are also social. Much of what unfolds in this food-competition experiment has to do with the social roles of the chimpanzees, that influence the subordinate chimpanzees’ perception with respect to possibilities for action (e.g., getting one food item as opposed to the other) and for interaction (e.g., avoiding repercussions from a dominant chimpanzee if the mutually visible food is selected). From previous interactions with the dominant chimpanzees and other group mates, the subordinate chimpanzees have become just that: subordinate. A subordinate’s perception of the mutually observable food item is already informed by her history of interactions. This is more than associative learning; in order to grasp the meaning of the situation at hand, one has to be able to interact with the other and in their shared world; one has to be able to perceive affordances defined by social context.

Although IT and BR views may be generally consistent with each other, crucially, the enactivist approach offers a specification about the meaning that is implicit in the action and potential interaction. The meaning isn’t deduced from a set of beliefs or rules, as if it were an abstract theoretical or intellectual process of puzzle-solving; and it is not simply the result of an association of a current situation with a past situation. It’s a matter of “practical or pragmatic (and specifically social) reason” (Gallagher and Povinelli 2012: 154) – being able to see what is possible in a socially constrained situation. Meaning, in this sense, affords certain implicit consequences that the perceiver is able to anticipate. Call et al. (2004), for example, found that chimpanzees became angry when an experimenter chose not to provide a reward to them – but not when she was unable to provide the reward. This suggests an awareness of what actions were available in their shared social world, and importantly, the responses from the chimpanzees modulated in accordance with changes to those social affordances (i.e., changes to how the chimpanzees could expect to interact with the experimenter). [For a related discussion of perspective-taking in chimpanzees, see Halina, Chapter 22 in this volume.]

A different kind of food-competition experiment offers additional support for the enactivist/IT interpretation. Kaminski et al. (2008) placed three cups between two chimpanzees, one subject and one competitor. The competitor, distracted by the researcher, was able to see the location of only one food item, while the subject was able to see both food items as they were placed into two of the three cups. In cases where the subject selected a cup first, she would pick the cup containing the food that the competitor knew was there – maximizing her potential for food acquisition. The researchers reject the ToM interpretation and conclude that “chimpanzees have a basic goal-perception psychology” (233). That is, chimpanzees can see what another’s goal is; they can see what the other sees of the situation (what it affords the other chimpanzee), without necessarily understanding any hidden mental states related to that goal. This is consistent with experimental data regarding chimpanzees tracking the gaze of humans, again suggesting an awareness of what others see, and therefore what their affordances are in the shared environment. In one study, for example, chimpanzees as young as 13 months engaged in gaze-tracking (Okamono et al. 2002); and in other studies, chimpanzees used the information gained by gaze-tracking to find food that was initially not visible to them (Itakura et al. 1999; Bräuer et al. 2005).

There is also evidence of chimpanzees responding differently to the affective states of conspecifics, displayed on the faces of those conspecifics. For example, Kano et al. (2008) found that chimpanzees were more likely to remember the photos of aggressive chimpanzees than of relaxed conspecifics. This is consistent with the enactivist view about direct social perception; the aggressive chimpanzees’ faces offer clearer information about social affordances and would therefore be more memorable or salient for the observing chimpanzee. In an actual interaction situation, in contrast to the experimental presentation of photos, this recognition would not be reduced to a pure association, since in such circumstances current affordances (and not just previous social contexts) are what primarily drive the effect.

The failing of false-belief tasks, too, can be explained through the lens of IT. For example, three-year-old children fail elicited false-belief tests (i.e., those in which experimenters ask the child for a judgment about the behavior of someone who is observed), although much younger infants at 13 months pass spontaneous false-belief tests (Onishi and Baillargeon 2005). In the spontaneous tasks, infants observe a toy being moved from a green box to a yellow box, unbeknownst to an agent returning to the room with the false belief that the toy is still in the green box. Experimenters measure violation of expectation in terms of looking times or anticipated looking at targets to show that young infants anticipate that the agent will look in the original green box for the toy. The standard ToM interpretation is that the infant is a passive observer who infers that the agent has a false belief (Baillargeon et al. 2010). The BR interpretation is that the infant has already learned the rule that agents look for things where they last saw them, and they infer that is where the agent will look (Ruffman and Perner 2005; Perner and Ruffman 2005; Povinelli and Vonk 2003). Like the ToM interpretation, BR understands the process as inferential. Indeed, this account still requires inferences on the part of the infant (Heyes 2014).

In contrast to what would be demanded in terms of inferential ability by either ToM or BR interpretations in these cases, the enactivist IT interpretation maintains that since infants have interacted with others throughout their first year of life in very basic, embodied (primary intersubjective) engagements (Trevarthen 1979), their perceptions of others are already shaped in ways that recognize the possibilities afforded to others and to themselves by specific situations. That such possibilities for meaningful interactions with others shape the way that they perceive such situations is made clear in experiments that allow infants to interact with the agents (e.g., by directing the agent to the right box) (Buttelmann et al. 2009; Southgate et al. 2010). These experiments suggest that in their active response to the agent, infants discriminate between situations in which the agent has seen versus has not seen the toy being moved.

In an experiment with three-year-olds who typically fail the explicit false-belief test, Rubio-Fernández and Geurts (2013) allow the three-year-olds to interact with the agent, and they show that the more a three-year-old is able to act and interact in the situation, the more likely the child is able to get the right answer. Interaction not only allows the three-year-old to gain the right answer; it also helps to explain why the same three-year-old fails the explicit false-belief test. In the latter test, the child is interacting only with the experimenter, answering her questions, and not with the agent whose behavior he is asked to predict from a third-person perspective. The saliency of the second-person interaction with the experimenter, and the social affordances connected with it, however, bias the child’s answer towards what both the experimenter and the child know – the actual location of the toy – which then motivates the wrong answer (Gallagher 2015). As Ciaunica (2014) explains, in evolutionary terms of survival, the immediacy of intersubjective interaction takes priority over any merely observational task. In experiments that rearrange the task to make the interaction with the experimenter support (rather than distract from) the child’s ability to track the perspective of the agent (e.g., Rubio-Fernández and Geurts 2013), the three-year-old passes the false-belief test.

If we extrapolate from what seems to be happening in the human child case to what might be the problem in the chimpanzee case, a potential answer emerges as to why chimpanzees struggle with false-belief tasks. In the Call and Tomasello (1999) study, one problem may be that the salience of the communicative interaction between chimpanzee and communicator may bias the chimpanzee into following the lead of the communicator’s behavior, even when the communicator has not seen the location change. Another problem may be that the kind of situation confronting the chimpanzee, both in terms of problem-solving and in terms of social (intersubjective) structure is significantly different from primary intersubjective situations in the wild. While human infants have a year of primary intersubjective interactions shaping their perception, it is not clear that primary intersubjectivity is the same for chimpanzees, so the specific situations of false-belief tests may not offer the same affordances (or are not necessarily as meaningful) as for human infants.

We note that most of the chimpanzee experiments that have been completed involve interspecies tasks; we should not be surprised to see different results emerge if, in addition to the food-competition design, more experimental designs emerge that rely on intraspecies interaction. Action and interaction affordances, and therefore possible responses, may be different in interspecies versus intraspecies situations. As Byrne and Whiten (1992) noted, following Jolly (1966) and Humphrey (1976), primates in naturalistic settings do not encounter the kinds of technical challenges that many of our existing experimental designs employ; rather, primates tend to respond to social problems (e.g., avoidance of conflict). Especially when we consider the fact that experimental designs take chimpanzees out of the wild and remove them from their pre-existing social groups, we should expect to see our results affected by both the nature of the tasks with which they are presented and their removal from naturalistic settings.

We also note that the importance of the false-belief task is a matter of debate. Some philosophers who study social cognition in nonhuman animals have called for a new experimental paradigm in which implicit, violation-of-expectation tests replace standard, explicit false-belief tests (Andrews 2005; Lurz 2011). We want to go further and suggest that it is not clear that mental state attribution is of central importance for social cognition in either chimpanzees or humans. As Call and Tomasello remark at the end of their study, there is so much more to social cognition than mental state attribution (mindreading). Apes do have sophisticated cognitive and social abilities, some of which they share with humans, and some which may be quite different due to differences in affordances offered by their own natural environments. Call and Tomasello mention conspecific gaze-following, behavioral coordination during hunting, vocal and gestural communication with group mates, social learning, and joint actions in contests for dominance and resources: “These all involve understanding complex social situations and creating sophisticated social strategies for dealing with them” (1999: 394). They all involve sensory-motor capacities and embodied interactions that provide sufficient information relevant to the practical and social situation without the need for mindreading or worrying about false beliefs.

As philosophers, we need to make sense of what is obviously complex social cognition that may not amount to a proper ToM in chimpanzees. IT is able to acknowledge and can begin to make sense of the different, but still rich, meaning-laden social worlds that vary across species, while recognizing that humans alone may be capable of higher-order mindreading (available to us, for example, when direct perception fails).4

Notes

1 SG thanks the Humboldt Foundation’s Anneliese Maier Research Award for supporting his research on this topic.

2 But see Lavelle 2012 and Carruthers 2015 for the idea that we may have perceptual access to some mental states.

3 This claim has been met with some criticism (Carruthers 2008; Fitzpatrick 2009; Sober 2015).

4 Some clarification may be achieved by considering how IT relates to two other proposals. (1) Povinelli and Giambrone (1999) argue that in the human, an acquired ToM capacity with the possibility of reinterpreting behavior in terms of hidden mental states may come to co-exist with the primary behavioral-reading skills that characterize both chimpanzee and young infant behavior. (2) Likewise, Heyes and Frith (2014) suggest that the kind of explicit mindreading that starts around four years of age in humans, and that goes beyond the abilities of young infants, is a learned cultural skill (much like the skill of reading a text). IT can agree with all of these theorists on this point – that ToM is something learned as the child develops – with two important provisos: that learning this skill is very much informed by the interaction capacities of primary and secondary intersubjectivity found in human infants, and that mindreading does not typically become the default or automatic way that humans understand each other, as Povinelli and Eddy (1997) suggest.

Further reading

L. Barrett’s Beyond the Brain: How Body and Environment Shape Animal and Human Minds (Princeton, NJ: Princeton University Press, 2011) provides a provocative discussion of the evolution of minds and the relationship of minds to environments. For an interdisciplinary discussion of the importance of understanding the mind as embodied, see F. J. Varela, E. Thompson, and E. Rosch, The Embodied Mind (Cambridge, MA: The MIT Press, 1993). For an introduction regarding research on chimpanzee cognition, see E.V. Lonsdorf, S. R. Ross, and T. Matsuzawa, The Mind of the Chimpanzee: Ecological and Experimental Perspectives (Chicago: The University of Chicago Press, 2010). For a detailed discussion of the phenomenological tradition that informs IT, see S. Gallagher and D. Zahavi, The Phenomenological Mind, 2nd edition (New York: Routledge, 2012).

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