For social species, recognizing and adequately yet quickly responding to the emotions of others is crucial for their survival. The current study investigates attentional biases toward emotions in two closely related species, humans and chimpanzees. Prior research has demonstrated that humans typically show an attentional bias toward emotions. We here build on that literature by studying the underlying unconscious mechanisms within and across humans and chimpanzees and aim to gain insight into the evolutionary continuity of expressions. Experiment 1 tested whether chimpanzees show an attentional bias toward the expressions of conspecifics and whether this putative bias is modulated by the stimulus presentation duration, being 33 ms or 300 ms. The stimuli were followed by a visual mask in the form of a neutral body image. This backward-masking procedure eliminated the visibility of the stimuli that were presented for 33 ms, rendering their presentation subliminal. In contrast to our prediction, no attentional bias toward emotions was observed in chimpanzees. The goal of Experiment 2 was to verify this finding and to investigate chimpanzees' reaction to human stimuli. Replicating Experiment 1, no evidence of an attentional bias toward emotions was observed in chimpanzees. In Experiment 3 we used the same chimpanzee and human expressions in 711 museum visitors and confirmed that humans do have an attentional bias toward emotions. Interestingly, this bias was independent of the stimulus presentation duration and most strikingly, independent of the species that was observed. Implications for theorizing about species differences in attentional mechanisms in processing emotions are discussed, as well as directions for future research, to investigate our preliminary findings and this potential species difference further. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

We report on the development and testing of a portable touchscreen apparatus and accompanying software program for primate enrichment, cognitive research, and husbandry applications. For zoos considering using technology to bolster scientific efforts or enhance the welfare of primates in their care, touchscreen activities offer a solution that has a long and proven record of primate use in laboratory settings as well as a history of usage in the zoo world. We review the options that are available for zoos to build their own touchscreen systems and we offer as an alternative our pre-built apparatus, Apex, and primate software suite, ApeTouch, both of which are tailored for use in a zoo setting. The efficacy and utility of these tools are demonstrated in a training study with four macaque groups of different species that were previously naïve to touchscreens. All of the groups in the study learned to use the device and displayed a consistent engagement with the touchscreen tasks over 95 daily sessions of exposure. In the final stage of the training, two of the four groups displayed an above-chance level performance on a numerical sequencing task.

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The sequence of Arabic numerals from 1 to 19 was taught to six chimpanzees, three pairs of mother and child. Each chimpanzee participant sat facing a touchscreen on which the numerals appeared in random positions within an imaginary 5-by-8 matrix. They had to touch the numerals in ascending order. Baseline training involved touching the adjacent numerals from 1 to X or from the numeral X to 19. Systematic tests revealed the following results: (1) The range 1 to 9 was easier than 1 to 19. (2) Adjacent numerals were easier than nonadjacent ones. (3) The “masking” (memory task) caused deterioration of performance. All these factors depended on the number of numerals simultaneously presented on the screen. A chimpanzee named Pal mastered the skill of ordering two-digit numerals with 100% accuracy. Human participants were tested in the same experiment with the same procedure. Both species showed relative difficulty in handling two-digit numerals. Global–local information processing is known to be different between humans and other primates. The assessment of chimpanzee performance and comparison with humans were discussed in terms of the possible difference in the global–local dual information processing of two-digit numerals.