Effects of cage mesh on pointing: hand shapes in chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>)

It has been speculated that cage mesh exerts a shaping influence on reaching behavior by captive apes, which is then misconstrued as pointing by human observers. Although this notion is clearly falsified by the pointing of captive language-trained apes—who point in the absence of intervening cage mesh—nevertheless, the degree to which cage mesh might influence pointing hand shapes by captive great apes in other housing environments remains relatively unexplored. We examined 259 pointing gestures displayed in archival footage from over 18 h of observation by three nonlanguage-trained chimpanzees housed at a biomedical research center. We coded points in relation to how close to the boundaries of the diamond-shaped cage mesh their points were displayed. We found that points with the whole hand were significantly more likely to be displayed away from the mesh boundaries, relative to points with the index finger or other single-digit points. However, points of each hand shape were displayed at each location, demonstrating that these physical parameters do not fully account for the number of fingers extended while pointing by chimpanzees.     

Parent Education in a Group Therapy Setting

This article responds to K. Roy MacKenzie's Presidential Address, which concerns the challenge of mental health reform as it effects group psychotherapy. Issues of the time-effective use of groups for specific patient populations are explored. The need for practice guidelines that benefit from outcome studies is emphasized. In addition, the efforts of the National Registry of Certified Group Psychotherapists to support group therapy within the current managed care environment are explicated.     

The Effect of Hypophysectomy on Personality in Women with Metastatic Breast Cancer as Revealed by the Rorschach Test

This study tested the hypothesis that assertive and nonassertive people have different personality profiles and self-actualizing values. Results indicated that assertive and nonassertive groups differed significantly, in terms of their personality profiles based on the Personality Research Form, and their self-actualization profiles based on the Personal Orientation Inventory, supporting the tested hypothesis.     

The gesture ‘Touch’: Does meaning-making develop in chimpanzees’ use of a very flexible gesture?

Animal Cognition - In this bottom-up study of gesture, we focused on the details of a single gesture, Touch. We compared characteristics of use by three young chimpanzees with those of 11 adults,...     

The effect of question order on evaluations of test performance: Can the bias dissolve?

Question difficulty order has been shown to affect students’ global postdictions of test performance. We attempted to eliminate the bias by letting participants experience the question order manipulation multiple times. In all three experiments, participants answered general knowledge questions and self-evaluated their performance. In Experiment 1, participants studied questions and answers in easy–hard or hard–easy question order prior to taking a test in the same order. In Experiment 2, participants took the same test twice in the opposite question order (easy–hard then hard–easy, or hard–easy then easy–hard). In Experiment 3, participants took two different tests in the opposite question order (easy–hard then hard–easy, or hard–easy then easy–hard). In all three experiments, we were unable to eliminate the bias, which suggests that repeated exposure is insufficient to overcome a strong initial anchor.     

Aping expressions? Chimpanzees produce distinct laugh types when responding to laughter of others

Humans have the ability to replicate the emotional expressions of others even when they undergo different emotions. Such distinct responses of expressions, especially positive expressions, play a central role in everyday social communication of humans and may give the responding individuals important advantages in cooperation and communication. The present work examined laughter in chimpanzees to test whether nonhuman primates also use their expressions in such distinct ways. The approach was first to examine the form and occurrence of laugh replications (laughter after the laughter of others) and spontaneous laughter of chimpanzees during social play and then to test whether their laugh replications represented laugh-elicited laugh responses (laughter triggered by the laughter of others) by using a quantitative method designed to measure responses in natural social settings. The results of this study indicated that chimpanzees produce laugh-elicited laughter that is distinct in form and occurrence from their spontaneous laughter. These findings provide the first empirical evidence that nonhuman primates have the ability to replicate the expressions of others by producing expressions that differ in their underlying emotions and social implications. The data further showed that the laugh-elicited laugh responses of the subjects were closely linked to play maintenance, suggesting that chimpanzees might gain important cooperative and communicative advantages by responding with laughter to the laughter of their social partners. Notably, some chimpanzee groups of this study responded more with laughter than others, an outcome that provides empirical support of a socialization of expressions in great apes similar to that of humans.     

Perceived differences between chimpanzee (Pan troglodytes) and human (Homo sapiens) facial expressions are related to emotional interpretation

Human face perception is a finely tuned, specialized process. When comparing faces between species, therefore, it is essential to consider how people make these observational judgments. Comparing facial expressions may be particularly problematic, given that people tend to consider them categorically as emotional signals, which may affect how accurately specific details are processed. The bared-teeth display (BT), observed in most primates, has been proposed as a homologue of the human smile (J. A. R. A. M. van Hooff, 1972). In this study, judgments of similarity between BT displays of chimpanzees (Pan troglodytes) and human smiles varied in relation to perceived emotional valence. When a chimpanzee BT was interpreted as fearful, observers tended to underestimate the magnitude of the relationship between certain features (the extent of lip corner raise) and human smiles. These judgments may reflect the combined effects of categorical emotional perception, configural face processing, and perceptual organization in mental imagery and may demonstrate the advantages of using standardized observational methods in comparative facial expression research.     

Visual stability with goal-directed eye and arm movements toward a target displaced during saccadic suppression

This experiment tested whether the perceived stability of the environment is altered when there is a combination of eye and visually open-loop hand movements toward a target displaced during the eye movements, i.e., during saccadic suppression. Visual-target eccentricity randomly decreased or increased during eye movements and subjects reported whether they perceived a target displacement or not, and if so, the direction of the displacement. Three experimental conditions, involving different combinations of eye and arm movements, were tested: (a) eye movements only; (b) simultaneous eye and rapid arm movements toward the target; and (c) simultaneous eye and arm movements with a restraint blocking the arm as soon as the hand left the starting position. The perceptual threshold of target displacements resulting in an increased target eccentricity was greater when subjects combined eye and arm movements toward the target object, specially for the no-restraint condition. Subjects corrected most of their arm trajectory toward the displaced target despite the short movement times (average MT = 189 ms). After the movements, the null error feedback of the hand's final position presumably overlapped the retino-oculomotor signal error and could be responsible for the deficient perception of target displacements. Thus, subjects interpreted the terminal hand positions as being within the range of the endpoint variability associated with the production of rapid arm movements rather than as a change of the environment. These results suggest that a natural strategy adopted for processing spatial information, especially in a competing situation, could favour a constancy tendency, avoiding systematic perception of a change of environment for any noise or variability at the central or peripheral levels.     

Timing and accuracy of visually directed movements in children: control of direction and amplitude components

The reaction times (RTs), movement times (MTs), and final accuracy of hand movements directed towards visual goals were measured in 6-, 8-, and 10-year-old children, using tasks in which direction and amplitude components of movement were distinctly required. The tasks were performed with and without visual feedback of the limb. RTs decreased with age, and were shorter in directional than in amplitude task, in all ages. MTs were the longest at age 8 in both tasks, equally short at ages 6 and 10 in the directional task, the shortest at age 10, and intermediate at age 6, when amplitude had to be regulated. In the amplitude task, the target distance generally affected MTs under both visual conditions, but to a lower degree at age 10 than in the two younger groups. Movement accuracy, which was in all cases higher with visual feedback, showed different developmental trends among the two spatial components: directional accuracy was not different among the three groups of age, whereas amplitude accuracy showed a nonmonotonic development in the nonvisual condition, with an increase between age 6 and age 10, and the lowest level at age 8. In the visual condition, amplitude accuracy did not change with age. The specification of direction seems therefore to predominantly load the preparatory stage of the response. Amplitude specification seems to be more dependent on on-going regulations and to undergo a longer and more complex development, with a critical period around age 8 when a greater propensity for a feedback-based control appears on the two components. With increasing age, amplitude tends to be specific to a greater extent by a feedforward process.     

The role of movement speed in learning a visuo-manual coordination in children

Summary The aim of the present study was to investigate the processes underlying aiming movements (motor programming and feedback control), and to explore their modification through learning. Two groups of 6- and 9-year-old children were asked to perform a directional aiming task without visual feedback (open-loop situation). After 15 trials (pretest) all subjects were submitted to a practice session which consisted of three series of trials with visual feedback (closed-loop situation). Half of the subjects had to perform the task at maximum speed (programmed movements), while the other half was required to perform slow movements (feedback-controlled movements). After the practice session all subjects were tested again in the openloop situation without time constraints (posttest). The results showed that during the practice session, accuracy was greater than in the two test conditions. It was greater in the case of slow movements than in the case of rapid ones. Moreover, in the case of rapid movements, it did not improve over the three practice series, while it did improve with slow movements. The difference between pre- and posttests showed that both groups improved their accuracy with practice in all conditions, the greatest improvement being obtained with rapid practice movements in 9-year-old children. It is suggested that different types of feedback (on-line and delayed feedback) contribute in varying degrees to the improvement of the aiming movements. However, the rapid movement condition, which requires a greater efficiency of programming, was found to be more effective for learning than the slow movement condition. The age-related differences found in learning suggest that feedback information can be fully integrated into motor programming only after 6 years of age.