Social context shapes cognitive abilities: associative memories are modulated by fight outcome and social isolation in the crab Neohelice granulata

Abstract

Cognitive abilities of an animal can be influenced by distinct social experiences. However, the extent of this modulation has not been addressed in different learning scenarios: are all tasks similarly affected by social experiences? In the present study, we analyzed the effect of social dominance in aversive and appetitive memory processes in the crab Neohelice granulata. In addition, we studied the influence of social isolation on memory ability. Social dominance experiments consisted of an agonistic phase immediately followed by a memory phase. During the agonistic phase, matched pairs of male crabs were staged in 10-min encounters and the dominant or subordinate condition of each member of the dyad was determined. During the memory phase, crabs were trained to acquire aversive or appetitive memory and tested 24 h later. Results showed that the agonistic encounter can modulate long-term memory according to the dominance condition in such a way that memory retention of subordinates results higher than their respective dominant. Remarkably, this result was found for both aversive and appetitive memory tasks. In addition, we found that isolated animals showed no memory retention when compared with animals that remained grouped. Altogether this work emphasizes the importance of social context as a modulator of cognitive abilities.

Face-to-face configuration in Japanese macaques functions as a platform to establish mutual engagement in social play

Abstract

A face-to-face configuration and eye-to-eye contact are considered a basis for intersubjectivity, as they create a situation in which interactants are mutually attentive. Studies in humans have shown that the face-to-face configuration establishes active engagement by interactants in subsequent interactions, but it is not clear whether a similar function exists in non-human animals. Using data from a group of Japanese macaques (Macaca fuscata), this study compared dyadic play fighting sessions preceded and not preceded by a face-to-face configuration. During play fighting, players compete to gain an advantage over their playmates by attacking them unilaterally (i.e., attacking them without being attacked or pinning them to the ground). Defining the inter-player asymmetry of active engagement in play in terms of the difference in the duration of each individual’s advantage over the other, we found that asymmetry was lower in play bouts with a face-to-face beginning than in play bouts without one. Additionally, in play bouts not preceded by a face-to-face configuration, individuals who faced their partner at the onset of play unilaterally attacked their partner for a significantly longer duration than did those who did not face their partner at the onset of play. Conversely, in play bouts preceded by a face-to-face configuration, there was no difference in the duration of unilateral attacks. Overall, our results indicated that the face-to-face configuration in Japanese macaques functions as a platform to establish mutual engagement by interactors and enhances symmetry within play interaction.

2D or not 2D? An fMRI study of how dogs visually process objects

Abstract

Given humans’ habitual use of screens, they rarely consider potential differences when viewing two-dimensional (2D) stimuli and real-world versions of dimensional stimuli. Dogs also have access to many forms of screens and touchpads, with owners even subscribing to dog-directed content. Humans understand that 2D stimuli are representations of real-world objects, but do dogs? In canine cognition studies, 2D stimuli are almost always used to study what is normally 3D, like faces, and may assume that both 2D and 3D stimuli are represented in the brain the same way. Here, we used awake fMRI in 15 dogs to examine the neural mechanisms underlying dogs’ perception of two- and three-dimensional objects after the dogs were trained on either two- or three-dimensional versions of the objects. Activation within reward processing regions and parietal cortex of the dog brain to 2D and 3D versions of objects was determined by their training experience, as dogs trained on one dimensionality showed greater differential activation within the dimension on which they were trained. These results show that dogs do not automatically generalize between two- and three-dimensional versions of object stimuli and suggest that future research consider the implicit assumptions when using pictures or videos.