Mean performance on each expression category on Session 1 and on the final, criterion session. These findings provide a strong argument for the need to more fully understand how chimpanzees process their own facial expressions, what the role of configural processing is in expression categorization and whether chimpanzees are as sensitive to individual movements as humans. Results from this study showed that the most salient features were AU27 and, to a lesser extent, AU Figure 2 shows such a comparison where the human images are taken directly from the FACS manual Ekman et al. Intramuscular electrical stimulation of facial muscles in humans and chimpanzees: Ekman P, Rosenberg E, editors. They used a special coding system that reveals very subtle changes in facial movements.
Understanding the evolution of human emotional communication through chimpanzee facial expressions
This was done using subjects' performance on the upright training trials obtained during Experiment 2. The influence of social context on the use of blended and graded facial displays in chimpanzees Pan troglodytes International Journal of Primatology. Ekman P, Rosenberg E, editors. Chimps employ a rich variety of gestures and facial expressions to keep in touch with each other, and more importantly, there is intelligence behind the exchanges that makes for a level of understanding unseen elsewhere in the animal world. The authors of this study investigated whether chimpanzees produce the same types of facial expressions with and without accompanying vocalizations, as do humans. Figure 6 plots the results of the MSD analysis showing the perceived dissimilarity among expressions.
Chimpanzee flexibly use facial expressions and vocalizations | EurekAlert! Science News
An effect of expertise. Among skeletal musculature, facial muscles are unique because they attach into the skin of the face and scalp, controlling size and shape of the openings for the eyes, external nares, and mouth. Table 1 lists the mean performance by subjects for each expression dyad on the session when they met the final criteria. The comparison stimuli were presented in the corners of the monitor such that the images were across from one another and equidistant from the sample, that is, bottom left and right, upper and lower left, upper and lower right, and top left and right. Mean performance on upright versus inverted images of each expression category.
An illustration of each prototypical expression configuration and the percentage of category agreement between AU codes and a priori classifications can be seen in Figure 1. Finally, it reviews previous studies on the categorization of facial expressions by chimpanzees using computerized tasks, and discusses the importance of configural processing for this skill in both humans and chimpanzees. Gothard, Erickson, and Amaral used a similar visual eye-tracking procedure in rhesus monkeys but, in contrast to Nahm and colleagues, found greater exploration of the eye region for lip-smack displays and the greatest mouth exploration for bared-teeth displays. The lip-funneler AU22 movement was most salient for discriminations of whimper compared to the lip retraction AU Many linguists still believe that apes have no real grasp of human language, but are merely imitating their human companions.