Testing the Relationship Between Looking Time and Choice Preference in Long-tailed Macaques

Abstract

Visual bias in social cognition studies is often interpreted to indicate preference, yet it is difficult to elucidate whether this translates to social preference. Moreover, visual bias is often framed in terms of surprise or recognition. It is thus important to examine whether an interpretation of preference is warranted in looking time studies. Here, using touchscreen training, we examined (1) looking time to non-social images in an image viewing task, and (2) preference of non-social images in a paired choice task, in captive long-tailed macaques, Macaca fascicularis. In a touchscreen test phase, we examined (3) looking time to social images in a viewing task, and (4) preference of social images in a paired choice task. Finally, we examined (5) looking time to social images in a non-test environment. For social content, the monkeys did not exhibit clear preferences for any category (conspecific/heterospecific, in-group/outgroup, kin/non-kin, young/old) in the explicit choice paradigm, nor did they differentiate between images in the viewing tasks, thus hampering our interpretation of the data. Post-hoc analysis of the training data however revealed a visual bias towards images of food and objects over landscapes in the viewing task. Similarly, across choice-task training sessions, food and object images were chosen more frequently than landscapes. This suggests that the monkeys’ gaze may indeed indicate preference, but this only became apparent for non-social stimuli. Why these monkeys had no biases in the social domain remains enigmatic. To better answer questions about attention to social stimuli, we encourage future research to examine behavioral measures alongside looking time.

The evolutionary origins of syntax: Event cognition in nonhuman primates

“…Comparative research is most productive if different species can be tested with ecologically relevant problems presented to them in a comparable way ( 133 – 135 ). Recent advances in eye tracking ( 111 , 121 , 136 , 137 ) and touchscreen technology ( 66 , 138 , 139 ) render such an approach both feasible and simple to implement in a noninvasive setting. For example, eye tracking studies suggest that apes may be able to perform high-level theory of mind assessments, such as understanding false belief, at an implicit level ( 136 , 140 , 141 ), and these implicit responses may also extend to Old World monkeys ( 142 ).…”

“…These findings, which have advanced our understanding of apes’ perceptions of others’ actions through the use of eye tracking, indicate that exploring fine-grained species’ differences in temporal event sequences is a promising avenue for understanding the evolution of event cognition. The use of touchscreens could expound on eye tracking by examining explicit preferences ( 66 ) for agents or patients. One problem with many cognitive studies in primates is that they examine responses to human actors rather than to conspecifics, which could confound results ( 143 ).…”

“…The authors propose that the causal pattern is recognizable and thereby produced a more rapid habituation than the noncausal movement. However, the limitation of looking time paradigms is that they reveal little about the underlying motivation for visual bias ( 66 ); thus, interpretations can only be made with caution.…”

The use of gaze to study cognition: limitations, solutions, and applications to animal welfare

“…It is through interpretive differences about underlying psychological and physiological states that this method becomes conceptually problematic. That is, preferential looking paradigms only demonstrate that a pair of stimuli can be discriminated, not why the stimuli are discriminated ( Aslin, 2007 ; Tafreshi et al, 2014 ; Wilson et al, 2021 ). A study group might look longer at images of out-group members because to different individuals they are novel, threatening or attractive ( Fujita, 1987 ; Méary et al, 2014 ).…”

“…From a broader perspective, it is paradoxical that the same response - visual bias - can varyingly be interpreted to indicate preference, interest, novelty, surprise or even levels of anxiety ( Bethell et al, 2012 ; Tafreshi et al, 2014 ; Wilson et al, 2021 ); indeed, the use of the phrasing “preferential looking” is in itself misleading, as it imparts an element of choice in responses when they may be purely reflexive ( Winters et al, 2015 ; Wilson et al, 2021 ). It also implies that visual bias is due to preference rather than avoidance.…”