The importance of witnessed agency in chimpanzee social learning of tool use

Abstract

Social learning refers to individuals learning from others, including information gained through indirect social influences, such as the results of others’ actions and changes in the physical environment. One method to determine the relative influence of these varieties of information is the ‘ghost display’, in which no model is involved, but subjects can watch the results that a model would produce. Previous research has shown mixed success by chimpanzees (Pan troglodytes) learning from ghost displays, with some studies suggesting learning only in relatively simple tasks. To explore whether the failure of chimpanzees to learn from a ghost display may be due to neophobia when tested singly or a requirement for more detailed information for complex tasks, we presented ghost displays of a tool-use task to chimpanzees in their home social groups. Previous tests have revealed that chimpanzees are unable to easily solve this tool-use task asocially, or learn from ghost displays when tested singly, but can learn after observing conspecifics in a group setting. In the present study, despite being tested in a group situation, chimpanzees still showed no success in solving the task via trial-and-error learning, in a baseline condition, nor in learning the task from the ghost display. Simply being in the presence of their group mates and being shown the affordances of the task was not sufficient to encourage learning. Following this, in an escalating series of tests, we examined the chimpanzees’ ability to learn from a demonstration by models with agency: (1) a human; (2) video footage of a chimpanzee; (3) a live chimpanzee model. In the first two of these ‘social’ conditions, subjects showed limited success. By the end of the final open diffusion phase, which was run to determine whether this new behavior would be transmitted among the group after seeing a successful chimpanzee use the task, 83% of chimpanzees were now successful. This confirmed a marked overall effect of observing animate conspecific modeling, in contrast to the ghost condition. This article is part of a Special Issue entitled: insert SI title.

Acquisition of a socially learned tool use sequence in chimpanzees: Implications for cumulative culture

“…Overall, witnessing video demonstrations of the unscrew and suck behavioral sequence did not facilitate the further diffusion of this behavior in our seeded groups as compared to Phase 1. This is in line with the finding that chimpanzees, when presented with a complex task, are more successful in learning from a live chimpanzee model than from video demonstrations (Hopper, Lambeth, Schapiro & Whiten, 2015). …”

Experimental studies illuminate the cultural transmission of percussive technologies inHomoandPan

“…Alternatively in 'ghost experiments' only the results of complex tool-based actions are presented, so only emulation (not imitation) is possible, and here chimpanzees have failed to master tasks based on this information alone; instead they appear to need to learn from an agent actually performing the act [49,50]. Other experiments, manipulating the perceptible evidence of causal relations in a tool-based task, have revealed a switch from relatively complete imitation of a programme or sequence of component acts in the opaque case to a more emulative response where transparency reveals that some action elements are redundant [51] (children and even human adults, by contrast, will imitate in more blanket fashion independently of such contextual variations [51,52], a phenomenon dubbed 'over-imitation' that we shall return to when examining experiments on humans learning to knap flint).…”

Chimpanzees demonstrate individual differences in social information use

“…Only conditions in which individuals were exposed to either a live or video demonstration by a conspecific were included (i.e. no asocial controls, no human-led training, nor ‘ghost’ conditions, see Hopper et al 2015). …”

“…SIS = 0: individual shows no evidence or ambiguous evidence. The same criteria applied to all experimental conditions within a studyStudyData collectionSISScore criteriaHopper et al (2015)09/20051Used the seeded method on their first trial0Either never opened the puzzle-box or did not use seeded method on first trialHopper et al (2007)02/20061Used the seeded method on their first trial0Either never opened the puzzle-box or did not use seeded method on first trialHopper et al (2008)04/20061Used the seeded method on their first trial0Either never opened the puzzle-box or did not use seeded method on first trialHopper et al (2012)05/20061Used the seeded method on their first trial0Either never opened the puzzle-box or did not use seeded method on first trialWhiten et al (2007)06/20061Learned seeded method of opening a puzzle-box0Did not learn seeded methodDean et al (2012)06/20071Reached at least ‘level one’ of opening a three-stage puzzle-box0Did not reach level oneKendal et al (2015)10/20071Used the seeded method on their first trial0Either never opened the puzzle-box or did not use seeded method on first trialPrice et al (2009…”

“…This presents an unprecedented opportunity to examine individual performance of the same individuals across many studies. The National Center for Chimpanzee Care in Texas is one such site, where 16 experimental studies (one unpublished) have investigated social learning over a 12-year period (Davis et al 2016; Dean et al 2012; Hopper et al 2007, 2008, 2012, 2015; Kendal et al 2015; Price et al 2009; Vale et al 2014, 2017c; Watson et al 2017a, 2018; Whiten et al 2007; Wood 2013, thesis available at http://www.etheses.dur.ac.uk/7274). We collated these data to investigate whether chimpanzees demonstrate individual differences in their propensity for using social information from conspecifics to solve experimental problems and if so, which characteristics may covary with this propensity.…”