Does inequity aversion depend on a frustration effect? A test with capuchin monkeys (Cebus apella)

Brosnan and de Waal (Nature 425:297–299, 2003) reported that if a witness monkey saw a model monkey receive a high-value food, the witness was more inclined to reject a previously acceptable, but low-value food. Later work demonstrated that this alleged inequity aversion might be due to frustration induced by switching subjects from their role as models receiving a high-value food to the role of witnesses receiving a low-value food. In the present study, pairs of female capuchins exchanged a token for either a high- or a low-value food without switching their model–witness roles. Witnesses could exchange a token for a low-value food after an adjacent model had exchanged a token for the same food (Equity Condition) or for a high-value food (Inequity Condition). Failure- and latency-to-exchange measures showed that witnesses were unaffected by the food type offered to models (no inequity aversion). Moreover, models were unaffected by their history of food type offered (no frustration). These results join earlier work suggesting that alleged inequity effects depend on frustration-induction procedures. Furthermore, inequity effects sometimes fail to emerge because frustration induction in nonhuman primates is labile. This study complied with protocols approved by the Italian Health Ministry and all procedures were performed in full accordance with the European law on humane care and use of laboratory animals.     

Social facilitation of eating novel food in tufted capuchin monkeys (Cebus apella): input provided by group members and responses affected in the observer

Learning about food palatability from watching what conspecifics eat might be one of the advantages of group living. A previous study investigated whether group members' presence or eating activity account for social facilitation of eating of foods never previously tasted. Capuchins encountered novel colored foods when (1) alone (Alone condition) or (2) with group members visible in the nearby cage (Group-present condition) or (3) with group members present and eating a familiar food that had not been colored (Group+food condition). Social facilitation of eating occurred when group members were eating, despite the difference in color between the familiar food eaten by them and the novel food presented to the experimental subject. To clarify what subjects learnt from group members when social facilitation occurred, we further analyze here the data from the previous study. The number of visual exposures to the colored novel food (as a group member) correlated with increased consumption of that novel food when encountered later (as experimental subject). In contrast, the number of times that an individual fed on the familiar food (as a group member) did not decrease its consumption of novel food (as experimental subject). Therefore, capuchins (1) habituated to the colors of the novel foods, and (2) did not take into account that seeing group members eating a food does not provide information about the palatability of a differently colored food. Since social facilitation of eating occurs when foods do not match in color, at least in capuchins, social facilitation of eating should not be considered as a way of learning about a safe diet, but rather as a way of overcoming neophobia. Accepted after revision: 18 August 2001 Electronic Publication     

Theory‐Driven Subgroup‐Specific Evaluation of an Intervention to Reduce Private Car Use1

In the context of a 2‐wave panel study, we used Ajzen's (1991) theory of planned behavior (TPB) as the theoretical framework for deriving and systematically testing hypotheses as to how an intervention (a “free” ticket for public transportation) influences the travelmode choice of students. The empirical results show that this intervention caused a drastic decrease in students' car use. The effect of the intervention on behavior is mediated by the causal chain postulated by the TPB. In the second step, we analyzed whether there were subgroup‐specific reactions to the intervention. Surprisingly, the subgroup analysis shows that students with more negative attitudes toward policy measures restricting car use reacted more strongly to the intervention than did students with a more positive attitude.     

Information Integration in Modulation of Pragmatic Inferences During Online Language Comprehension

Upon hearing a scalar adjective in a definite referring expression such as “the big…,” listeners typically make anticipatory eye movements to an item in a contrast set, such as a big glass in the context of a smaller glass. Recent studies have suggested that this rapid, contrastive interpretation of scalar adjectives is malleable and calibrated to the speaker's pragmatic competence. In a series of eye‐tracking experiments, we explore the nature of the evidence necessary for the modulation of pragmatic inferences in language comprehension, focusing on the complementary roles of top–down information ‐ (knowledge about the particular speaker's pragmatic competence)  and bottom‐up cues  (distributional information about the use of scalar adjectives in the environment). We find that bottom‐up evidence alone (e.g., the speaker says “the big dog” in a context with one dog), in large quantities, can be sufficient to trigger modulation of the listener's contrastive inferences, with or without top‐down cues to support this adaptation. Further, these findings suggest that listeners track and flexibly combine multiple sources of information in service of efficient pragmatic communication.     

Kinematics properties of rapid aimed hand movements

Generalized motor program theory and the models of Schmidt, Zelaznik, and Frank (1978), and Meyer, Smith, and Wright (1982) of speed-accuracy relationships in aimed hand movements require that the underlying acceleration-time patterns exhibit time rescalability, in which all acceleration-time functions in an aimed hand movement are generated from one rescalable pattern. We examined this property as a function of movement time in Experiment 1, and as a function of movement time and movement distance in Experiment 2. Both experiments failed to demonstrate strict time rescalability in acceleration-time patterns, with the time to peak positive acceleration being invariant across movement time. This suggests that time rescalability is not a necessary condition for the linear relation between speed and spatial variability. A second major finding was that the variability in distance traveled at the end of positive acceleration was independent of movement time, contrary to the symmetric-impulse-variability model of Meyer et al. (1982). The findings of both experiments suggest that the processes involved in decelerating the limb play an important, but yet to be understood, role in determining the linear speed-accuracy trade-off. Finally, these results suggest that generalized motor programs are not based on simple, time-rescalable acceleration patterns.     

Application of the Theory of Planned Behavior to Adolescents’ Condom Use: A Panel Study1

The authors report a longitudinal study of factors determining use of condoms with new sexual partners in a representative sample of 650 German youth. Measures derived from the theory of planned behavior (Ajzen, 1985) were obtained in 2 waves separated by 1 year. Consistent with the theory, intentions to use condoms could be predicted from attitudes, subjective norms, and perceived behavioral control with respect to this behavior; and actual condom use was strongly related to intentions and perceptions of control assessed in Wave 2. Due to changes in beliefs and attitudes over time, only about 10% of the variance in reported condom use was accounted for by intentions and perceived control assessed 1 year earlier. Reported condom use was found to exert a direct effect on later intentions, unmediated by their hypothesized antecedents. Theoretical and practical implications of these findings are discussed.     

Category typicality effects in episodic memory: Testing models of distinctiveness

Middle Tennessee State University, Murfreesboro, Tennessee Category typicality effects were investigated within the context of three models of distinctiveness: a univariate model, a fixed-multifeature model, and a weighted-multifeature model. High-typical, medium-typical, and atypical targets were embedded in lists containing a background set of mediumto high-typicality items. Atypical items were more poorly recalled than were medium- and high-typical items independently of list structure. In recognition, subjects who studied high-typical items had difficulty discriminating between high-typical items that were and were not presented as part of the list. However, item typicality had little effect on the recognition performance of subjects who did not study high-typical items. These findings were consistent with the weighted-multifeature model of distinctiveness.     

Cognitive triad: Relationship to depressive symptoms,parents' cognitive triad,and perceived parental messages

Evaluating the relationship between children's depressogenic thinking, children's depressive symptoms, parents' depressogenic thinking, and perceived parental messages about the self, world, and future was the primary objective of this investigation. Children (n =133) from grades 4 to 7 completed measures of depression and anxiety, including a semistructured clinical interview, a measure of their cognitive triad, and a measure of perceived parental messages about the self, world, and future. Mothers (n =112) and fathers (n =95) completed a measure of their own cognitive triad. Results of a series of regression analyses revealed that (1) children's views of self, world, and future (cognitive triad) are related to severity of depression; (2) mothers' but not fathers' cognitive triads are related to their children's cognitive triads; (3) perceived parental messages to the children about the self, world, and future are predictive of the children's cognitive triads and ratings of depression; and (4) the relationship between perceived parental messages and depression is completely mediated by children's cognitive triads. Analyses of covariance indicated that the obtained mediational relationship between children's views of self, world, and future, perceived parental messages, and children's depressive symptoms was specific to depressive versus anxious symptomatology. Impfications for existing theory and research are discussed.