Remembering past exchanges: Apes fail to use social cues

Abstract

-Nonhuman primates can remember events from their distant past. Furthermore, they can distinguish between very similar events by the process of binding. So far, research into long-term memory and binding has focused on the binding of contextual information, such as spatial surroundings. As such, we aimed to investigate if apes can bind and retrieve other types of information, specifically, social information. We presented great apes with three different object types; they learnt to exchange (via reinforcement) one of the object types with one experimenter and another type with a second, different, experimenter. The remaining object type was not reinforced by either of the experimenters. After a delay of two or ten weeks, we assessed the apes' memory of which object type was exchanged with which experimenter. Additionally, we introduced a new experimenter to see if the apes could infer by exclusion that the remaining object type should be exchanged with the new experimenter. The apes successfully remembered which object types were exchanged, but failed to distinguish which object type was exchanged with whom. This failure to bind an object type to a specific person may have resulted from the apes learning to use a rule based on recency, as opposed to learning a conditional rule involving social information. However, results from a second experiment suggested they fail to incorporate social information even when no other information could guide successful performance. Our findings are consistent with research showing long-term memory in primates, but suggest that social information may not be bound in memory as readily as spatial or contextual information.

Long-Term Memory of Past Events in Great Apes

“…For instance, King (the gorilla) could remember what he had eaten and who had given him the food after a delay of 24 hr (Schwartz, Colon, Sanchez, Rodriguez, & Evans, 2002). However, a recent study by Lewis, Berntsen, and Call (2018) suggests that the who information must be salient to be successfully remembered, with apes failing to encode and remember who rewarded what, probably because the person was not a salient feature in the paradigm. This finding highlights the importance of carefully interpreting results in animal research in which subjects receive no instructions regarding what to attend to, and future research should clarify that a failure to remember is not just a failure to attend.…”

The cognitive challenges of cooperation in human and nonhuman animals

“…Perhaps because they do not form such enduring bonds with other individuals, rats base their decision to cooperate on the last encounter with their partner (using tit-for-tat like strategies) and not on the partner's overall level of cooperation 102 . Great apes remember past events for long periods of time 103,104 , but it is less clear how well and for how long they remember the social component of past events 105,106 . More studies requiring animals to encode social and non-social components of an event (especially a cooperative interaction) will further reveal the psychological basis of contingent cooperation in non-human animals.…”

Pet memoirs: The characteristics of event memories in cats and dogs, as reported by their owners

“…Clayton and Dickinson (1998) showed that scrub jays could recall the content of specific episodes (what-where-when information), a finding that has been replicated in numerous species (Babb & Crystal, 2006;Hoffman, Beran, & Washburn, 2009;Martin-Ordas, Haun, Colmenares, & Call, 2010). Other paradigms have investigated characteristics of episodic memory, such as temporal order (Schwartz, Hoffman, & Evans, 2005), free recall (Menzel, 1999), binding (Lewis, Berntsen, & Call, 2018;Martin-Ordas, Berntsen, & Call, 2013), spontaneous retrieval (Lewis, Call, & Berntsen, 2017b), distinctiveness (Lewis, Call, & Berntsen, 2017a), and unexpected recall (Zhou, Hohmann, & Crystal, 2012).…”