Humane Rather than Human Endpoints for Comparative Psychology
Abstract
Comparative psychology has been human-centric, focusing on an exploration of whether known human traits exist in other species. I propose to aim for a reduction in biases that form barriers to a better understanding of unique nonhuman cognitions, which can then enhance animal lives rather than using animals as tools to enrich our understanding of humans alone.
Keywords: anthropocentrism, multidisciplinary, evolution, diverse cognitions
For comparative psychology to flourish, it should embrace a multidisciplinary approach to studying animal minds and free itself from a solely psychological perspective. Perhaps because psychology is defined as the study of human behavior and mental processes, even the subdiscipline of comparative psychology is often narrowly focused on how the study of nonhuman species can inform an understanding of human psychology. For example, animals may be studied as models of human cognition or to determine when a uniquely human trait evolved (Bates & Byrne, 2007; Pongrácz et al., 2019). An alternative strategy is to attempt to understand animal minds in their own right by exploring the mechanisms underlying behavior that is typical for a study species, with the goal of understanding how and why that behavior evolved. For example, researchers have gained a better understanding of how cooperation can evolve by exploring the natural phenomenon of blood sharing in vampire bats (Carter, 2021). Such an approach will avoid some of the historical pitfalls of comparative psychology, such as poorly rationalized attempts to find evidence for traits thought to be uniquely human in species in which the trait could hardly be seen as relevant or expected. For example, why should nonhuman species exhibit mirror self-recognition? Why should primates learn a language based on vocalizations they cannot produce?
Although it is clearly of interest to determine the extent to which traits are shared across the animal kingdom, the default has often been to start with traits assumed unique to humans (or primates more broadly) rather than to acknowledge the possibility of traits and abilities that are unique to other species. In other life sciences (e.g., biology, zoology), diverse species are studied with the goal of understanding an organism’s place in broader ecological context, both within a snapshot in time and across evolutionary epochs. To allay concerns that this broader focus fails to contribute to an understanding of human psychology, it is important to note that understanding the selection pressures driving the evolution of an array of cognitive traits in various species betters our understanding of the selective pressures that may have shaped human psychology, specifically. For example, work on quantity discrimination across a multitude of species can indicate when humans may have begun to represent the abstract nature of number rather than solely observable indicators of quantity, such as area or mass (Bryer et al., 2022). Studying echolocation in bats and dolphins—a process that has no analog in primate cognition—can inform our understanding of navigation. This understanding can then be applied to solve human problems such as the design of man-made submarines and aircraft (Kim, 2015), much like the study of locomotion in insects has informed the field of biomechanics (Delcomyn, 2004).
In recent years, comparative psychology has merged more seamlessly with other life sciences, with it being more difficult to differentiate work originating from different disciplines. A greater focus on animal welfare and ethics have also fostered more overlap with veterinary science. Increased cross-talk between disciplines has led to greater representation of species and topics studied within comparative psychology such that the historical overrepresentation of nonhuman primates and laboratory species, such as rodents and pigeons, has given way to a field that is more broadly described as “comparative cognition,” as reflected in the call for commentaries in this issue. As such, comparative cognition would benefit from a wider recognition that there are many “cognitions” and that the human experience need not be the only frame of reference.
Awareness of complex cognitions and emotions in species both closely and distantly related to humans has led to an increased focus on concerns with animal welfare and ethics. Early in my career, I was chastised by a reviewer for referring to great apes by name and for citing a paper titled “Mental Time Travel …”. The tendency to diminish animal subjects to their role as subjects and to treat them as a means to an end is less prevalent today. These particular reviewers questioned the validity of studying topics such as metacognition and consciousness in nonhumans. Such narrowminded concerns would be unlikely today. If anything, the field currently is probably better characterized by a focus on complex cognition (i.e., processes that involve inference, reasoning, abstraction, and generalization; Vonk et al., 2021) and less characterized by a focus on basic learning processes (e.g., associative processes, such as conditioning). Metacognition (Beran, 2019) and previously taboo topics such as personality (Vonk & Eaton, 2018) are among many extremely productive current areas of study within comparative psychology. A willingness to explore other traits that were previously deemed unlikely in nonhumans will continue to uncover surprising insights about animal minds.
These shifts in attitudes about both the topics and subjects of study have made it easier to ask questions about complex abilities in nonhumans but increasingly difficult to conduct the type of invasive research that led to huge increments in our knowledge of both human and animal minds. Greater scrutiny of the conditions and ethics surrounding the care of animals in laboratories has accompanied challenges in funding laboratory work. In partial response to these mounting challenges, scientists have turned from a focus on laboratory animals to the study of species in zoological parks and sanctuaries, as well as companion animals (which may have seen the greatest growth in the past several decades). The resulting studies have revealed that humans may not be as unique as once postulated (Penn et al., 2008), but also that animals have many unique capacities of their own (Vonk & Povinelli, 2012).
Working with animals in less traditional settings has meant compromises to the systematic and rigorous control of subjects’ experiences. These subjects no longer exist solely to participate in human research. They may be less motivated to perform experimental tasks and more subject to distraction from external demands and activities. They will perform fewer trials in a day and can be tested on fewer days compared with laboratory subjects. The researcher has far less control over experiments conducted in nonlaboratory settings, but there are beneficial trade-offs. For example, these subjects ideally exist in more naturalistic social groups and may provide more valid data on social cognition and human–animal interactions. This type of research has the capacity to fascinate and engage the public, which may lead to increased efforts to protect the diversity of life on this planet so various species will be available to study for decades to come.
Studying animals outside of the lab reflects a return in some ways to the classic work by ethologists that inspired many of us to study animals in the first place. Field approaches, in particular, permit unique insight into the natural behavior of the organism, especially regarding social behavior. Comparative cognition has been heavily influenced by the social intelligence hypothesis put forth by Jolly (1966) and its variants (Dunbar, 1998, 2009; Humphrey, 1976), another factor in the overwhelming bias toward studying complex cognition in highly social species, such as primates, corvids, and dogs. It makes sense to examine social cognition in animals that live in social groups, but researchers have neglected other dynamics, such as mother/offspring and competitor relationships in less social species, as predictors of cognitive skills (Vonk & Edge, 2022a; Vonk et al., 2021). This bias has led to affirmations of the social intelligence hypotheses without the necessary “control groups,” violating the basic tenets of understanding causality (Mill, 1862). If one is to claim that social cognition is specific to social animals, one must make the necessary comparisons by studying the same processes in both highly social and less social species. Social cognition is woefully understudied in relatively solitary species like bears, for example, even though studying natural phenomena like the toleration of conspecifics during salmon fishing may shed light on the evolution of social processes such as cooperation (Stringham, 2012).
Perhaps in large part because of this focus on group-living as a predictor of complex cognition, researchers have often operated with the (sometimes implicit) assumption that two types of cognition (social and nonsocial) draw on distinct cognitive skills (Tomasello & Call, 1997). Researchers should question the validity of this misleading assumption and examine whether reasoning about social agents necessarily relies on fundamentally distinct processes from reasoning about nonsocial agents and events. Acknowledging that social and asocial species may share a set of capacities that can be applied to reason about either social or nonsocial events (Vonk et al., 2021) will free the field from possibly misleading dichotomies that limit fields of investigation (Vonk & Edge, 2022b).
A return to the study of basic mechanisms or underlying processes that give rise to various species-typical behaviors, as advocated by Tinbergen (1963) 60 years ago will help to reduce the biases guiding selection of study species. Comparative psychologists, myself included, have often chased the appearance of traits previously deemed unique to humans in less studied species as a way of advancing knowledge about how widespread various traits are. This is not to say that such explorations are lacking value, but they may be doubling down on some of the larger problems in the field. For one, researchers still have difficulty grappling with what has been deemed “Povinelli’s problem” (Lurz & Krachun, 2011), in which researchers cannot disentangle whether animals are reasoning about unobservable constructs or their observable correlates because the two necessarily covary (Povinelli, 2020). We will never make progress in understanding how other minds solve shared problems if we are biased to see every experimental outcome as evidence of humanlike cognitive processes. Instead, remaining open to the possibility that different cognitive processes may lead to the same outcomes will allow us to further our understanding of how diverse cognitions might emerge. For example, researchers recognized that many nonhuman species solved tests purporting to assess causal reasoning by employing proximity rules (Jacobs & Osvath, 2015) and that pigeons may succeed in matching to sample tasks not by viewing alternatives as potential matches to the target stimulus but instead by learning rules about the different configurations of the stimuli as a whole (Wright, 2001). If we begin by seeking traits that appear similar to those of humans and accept as confirmation of analogous processes any cursory evidence that animals make similar choices or enact similar behavior, we will be endlessly doomed to see animals as stepping stones en route to the evolution of humans without appreciating them for being their own end points; or, rather, stepping stones on their own journeys still in progress. This shift in perspective will inevitably lead to greater appreciation for our fellow species and a greater commitment to studying how we can improve their lives rather than how we can use them as tools to improve our own.
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