The use of individual, social, and animated cue information by capuchin monkeys and children in a touchscreen task

The distinctiveness of human cumulative culture raises the question of whether humans respond differently to information originating from social sources, compared with information from other sources. Further, does any such differential responding set humans apart from other species? We studied how capuchin monkeys and 2- to 5-year-old children used information originating from their own actions, those of a human demonstrator, or an animated cue. This information, presented via a touchscreen, always revealed in the first trial (T1) the reward value (rewarded or unrewarded) of one stimulus from a 2- or 3-item array, and could be used in a follow-up trial (T2) involving the same stimulus array. Two monkeys achieved a level of proficiency indicating their appreciation of the T1–T2 relationship, i.e., reliably repeating rewarded (“win”) selections and actively avoiding repetition of unrewarded (“lose”) selections well above chance levels. Neither the two task-proficient monkeys nor the children showed overall performance differences between the three source conditions. Non-task-proficient monkeys, by contrast, did show effects of source, performing best with individually-acquired information. The overall pattern of results hints at an alternative perspective on evidence typically interpreted as showing a human advantage for social information use.

Reward Does Not Modulate the Preview Benefit in Visual Search

Preview benefit refers to faster search for a target when a subset of distractors is seen prior to the search display. We investigated whether reward modulates this effect. Participants identified a target among non-targets on each trial. On “preview” trials, placeholders occupied half the search array positions prior to the onset of the full array. On “non-preview” trials, no placeholders preceded the full search array. On preview trials, the target could appear at either a placeholder position (old-target-location condition) or a position where no placeholder had been (new-target-location condition). Critically, the color of the stimulus array indicated whether participants would earn reward for a correct response. We found a typical preview benefit, but no evidence that reward modulated this effect, despite a manipulation check showing that stimuli in the reward-signaling color tended to capture attention on catch trials. The results suggest that reward learning does not modulate the preview benefit.

Orienting Attention to Locations in Internal Representations

Three experiments investigated whether it is possible to orient selective spatial attention to internal representations held in working memory in a similar fashion to orienting to perceptual stimuli. In the first experiment, subjects were either cued to orient to a spatial location before a stimulus array was presented (pre-cue), cued to orient to a spatial location in working memory after the array was presented (retro-cue), or given no cueing information (neutral cue). The stimulus array consisted of four differently colored crosses, one in each quadrant. At the end of a trial, a colored cross (probe) was presented centrally, and subjects responded according to whether it had occurred in the array. There were equivalent patterns of behavioral costs and benefits of cueing for both pre-cues and retro-cues. A follow-up experiment used a peripheral probe stimulus requiring a decision about whether its color matched that of the item presented at the same location in the array. Replication of the behavioral costs and benefits of pre-cues and retro-cues in this experiment ruled out changes in response criteria as the only explanation for the effects. The third experiment used event-related potentials (ERPs) to compare the neural processes involved in orienting attention to a spatial location in an external versus an internal spatial representation. In this task, subjects responded according to whether a central probe stimulus occurred at the cued location in the array. There were both similarities and differences between ERPs to spatial cues toward a perception versus an internal spatial representation. Lateralized early posterior and later frontal negativities were observed for both preand retro-cues. Retro-cues also showed additional neural processes to be involved in orienting to an internal representation, including early effects over frontal electrodes.