I would like to start by thanking the editors of The Brains Blog, especially Cameron Buckner, for giving me the opportunity to discuss some of the ideas I had about the human and ape minds while observing a group of mother and infant chimpanzees at Gombe National Park in Tanzania, Africa.
By the end of my first week of observations at Gombe, I was more exhausted than I had ever been in my life. I was constantly out of breath and wondering why anyone would think it was a good idea to send a philosopher to Gombe. Then I ran into a mother and infant chimpanzee. This was the first time I’d seen a chimpanzee in the wild, within arm’s reach. Even though the encounter lasted less than a minute, her gaze made a big impression on me. There was something in her eyes that I had never seen before. It is hard to describe without relying on empty platitudes, but I can tell you that it is different than the way a dog looks at you and it is different than the way a human looks at you. There was something else there. I experienced many wonderful and challenging things after that moment, but that first encounter has stayed with me.
Looking back at that moment, I realize that this experience was not only significant in terms of seeing a chimpanzee for the first time but also in terms of the immediate way in which I framed my experience. First, my immediate impulse was to situate the chimpanzee as similar to or different than me; second, my immediate focus was on the chimpanzee’s gaze; and last, I recognized how difficult it was to explain what was behind gaze. These three theoretical stances are the starting points of the themes I will explore in the following posts. I will examine how questions of continuity and human uniqueness in the evolution of cognition contain embedded presuppositions about perception, communication, and the development of the mind that have a significant impact on our understanding of social cognition. Using joint attention as an example of social cognition, I will show how the mode of perception and interaction chosen to describe the development of the mind has a deep influence on our understanding of the mind itself.
Joint attention (JA) refers to social partners paying attention to each other and coordinating their attention to an object/situation of interest. Researchers use behavioral cues, in particular, gaze following, as evidence of the mental capacities infants need for JA, such as knowing that others have perspectives different than theirs or knowing that others have intentionality. To understand the role played by JA in the development of the mind, several authors follow Seibert, Hogan and Mundy’s (1982) classification: Responds to Joint Attention (RJA), that is, infants respond to gaze shifting accompanied by head turns, and Initiating Joint Attention (IJA), that is, infants use eye contact and/or deictic gestures, such as pointing, to initiate coordinate attention with a partner. Both forms of JA are correlated with fundamental milestones in development such as language/symbolic development and social-cognitive development. For example, Mundy and Gomes (1998) have found a correlation between RJA and language acquisition. Charman et al. (2000) have argued that IJA is a predictor of Theory of Mind (ToM) performance, that is, how well infants understand others’ minds. Moreover, Tomasello (2014) believes that JA is what allows modern humans to develop true cooperation, language, and culture. For Tomasello, JA is part of an evolutionary process that allows humans to engage in cooperative communication, each other’s perspective, symbolic representation, recursive inferences and self-monitoring that facilitates the appearance of collective intentionality, a form of intentionality that allowed humans to create culture and conventional communication. Given these characteristics, JA is a fundamental element for understanding the human mind and its place with respect to other species.
To illustrate this point let’s examine in more detail Michael Tomasello’s account of what makes humans unique. In his latest book, Tomasello (2014) argues that great apes’ skills of social cognition evolved mainly for competing with others in the social group: being better or quicker than group mates at anticipating what potential competitors might do. This entails that, even though apes understand that others see things and can follow gaze direction, they cannot engage in JA.
Meanwhile, for Tomasello, humans attempt to coordinate their actions and intentional states with others via human-specific forms of collaboration that entail active cooperation and communication facilitated by JA. To understand these unique human abilities, Tomasello relies on gaze as a way of identifying cognitive abilities such as cooperation and joint attention. According to Tomasello, ontogenetically, human children begin to engage in JA via joint visual activities around 9-12 months. And, for this author, since there are no examples of this kind of visual JA in apes, there is a fundamental difference between apes and humans. Tomasello argues that, because of the benefits that these collaborations brought for early humans, it paid off in the human evolutionary path to “advertise” eye direction as a way of advertising internal states; according to Tomasello only humans have highly visible eye direction and only humans use this information.
This reliance on gaze as a window to the mind is not novel. From the beginning researchers who study joint attention have used gaze as the basis for determining whether an organism has a theory of mind and/or is capable of JA. In their seminal paper, Scaife and Bruner (1975) designed an experiment to understand JA through parent-infant face-to-face social interactions. This experiment became the standard paradigm of JA; since then researchers have been using gaze-following as a way to operationalize JA (see MacPherson & Moore, 2007 for a review). Moreover, gaze-following as been used to understand social aspects of certain disorders such as autism. For example, in his highly influential book Mindblindness, Baron-Cohen writes: “When I step back from the model of the mind reading system that I have proposed, EDD (Eye Direction-Detector) seems to stand out” (1997, p. 97).
However, there are three main difficulties in using gaze-following as a paradigm of JA in the context of understanding the development of the human mind from an evolutionary perspective. First, as D’Entremont et al. (2007) argue, this common adoption of the gaze-following paradigm is also characterized by a disagreement on whether a mentalist interpretation can be given of gaze-following; there is disagreement on whether gaze-following is the result of the infant acquiring an understanding of others as intentional beings. Moreover, from this perspective, the individual who exhibits JA through gaze-following, has to have complex cognitive abilities such as recognizing that looking is intentional behavior directed to external objects and events, and understanding that looking results in the mental experience of seeing.
This problematic relationship between mindreading and gaze has also been prevalent in animal studies, in particular in the debate on whether experimental evidence shows that animals know what others have seen or not seen and if the evidence shows that they posses theory of mind (see Andrews, 2005 and her excellent posts in The Brains Blog and Buckner, 2014 for a review of the cognitive and methodological implications of this debate). Authors on both sides of the argument rely on how chimpanzees interpret what they have seen or not seen. The same can be said about the debate of whether ape’s gaze is evidence of JA (Gomez, 2010; Carpenter & Call, 2015).
The second difficulty in using gaze-following as the paradigm for JA is that it requires a caregiver who assumes the responsibility of engaging the infant in this kind of behavior. According to Flom and Pick (2007), JA can only be started if a caregiver becomes responsible for coordinating an infant’s attention to look at an object of interest or at the caregiver. Meanwhile, one of the most surprising facts about mother and infant chimpanzee interaction in the wild is that mothers rarely use gaze as a form of interaction (personal observation, for a similar finding in monkeys see Perry and Manson, 2008). Thus, using gaze in this way requires a kind of caregiver interaction that is not likely to occur in apes.
Third, if gaze is the cornerstone of the human capacity of JA, then we would predict that infant-caregiver interaction will be predominantly characterized by visual interaction. However, through the examination of cross-cultural studies, is possible to argue that contrary to the above prediction, in many cultures the preferred method of interaction between caregiver and infant is not gaze but touch and that these infants are able to achieve similar milestones as infants from other cultures.
For example, mothers who belong to the Gussi community in Kenya (Le Vine, 2010) do not engage in face-to-face social communication with their infant, especially not in verbal exchanges, two cornerstone features of western mother-infant social interaction; instead Gussi mothers comfort infants through body contact day and night. However, these infants did not exhibit any significant differences compared with North American children as measured through the Neonatal Behavioral Assessment Scale (NBAS). In some cases the same cognitive skill is achieved through a different mode of interaction. For example, Childers et al., (2007) report that Ngas-speaking toddlers in Nigeria are carried in a cloth facing the back of the caregiver with no-eye-to-eye contact. These toddlers are unlikely to alternate their gaze between the toy and the adults in JA tasks; however, their JA behavior resembles patterns observed in other cultures.
These findings suggest that gaze cannot be used as the only mode to study mother-infant interaction. It seems that gaze is the preferred mode used by humans in urban western cultures (predominantly in urban western cultures such as the US and Germany; see Keller, et al., 2009 for an example) and by chimpanzees that have been reared by human caregivers (Bard, 2012). This is problematic because if we characterize development in this way, then from the initial conditions, we are restricting JA to a specific group of humans closing the possibility of finding it in diverse human cultures, other species or understanding its evolutionary process in a more gradual way. To be able to describe humans as a species of primates, it seems more adequate to also consider other modes of interaction, one that can be found in apes and across diverse human cultures.
In my next post, I will propose an alternative framework for the understanding of JA that accommodates these variations. Following recent studies on tactile perception, I will show how the infant, through this mode (in particular, through the affective touch of his/her caregiver), can develop similar capacities to the ones achieved in experiments that operationalize JA using gaze-following.
Andrews, K. 2005: Chimpanzee theory of mind: looking in all the wrong places? Mind & Language, 20(5), 521-536.
Bard, K.A. 2012: Emotional engagement: how chimpanzee minds develop. In F. de Waal & P. Ferrari (eds.), The Primate Mind: Built to Engage with Other Minds. Cambridge, MA: Harvard University Press.
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