Step changes in the intertrial interval in the midsession reversal task: Predicting pigeons' performance with the learning-to-time model

Our goal was to assess the role of timing in pigeons' performance in the midsession reversal task. In discrete-trial sessions, pigeons learned to discriminate between 2 stimuli, S1 and S2. Choices of S1 were reinforced only in the first half of the session and choices of S2 were reinforced only in the second half. Typically, pigeons choose S2 before the contingency reverses (anticipatory errors) and S1 after (perseverative errors), suggesting that they time the interval from the beginning of the session to the contingency reversal. To test this hypothesis, we exposed pigeons to a midsession reversal task and, depending on the group, either increased or decreased the ITI duration. We then contrasted the pigeons' performance with the predictions of the Learning-to-Time (LeT) model: In both conditions, preference was expected to reverse at the same time as in the previous sessions. When the ITI was doubled, pigeons' preference reversal occurred at half the trial number but at the same time as in the previous sessions. When the ITI was halved, pigeons' preference reversal occurred at a later trial but at an earlier time than in the previous sessions. Hence, pigeons' performance was only partially consistent with the predictions of LeT, suggesting that besides timing, other sources of control, such as the outcome of previous trials, seem to influence choice.     

Associative symmetry by pigeons after few-exemplar training

The present experiment investigated whether pigeons can show associative symmetry on a two-alternative matching-to-sample procedure. The procedure consisted of a within-subject sequence of training and testing with reinforcement, and it provided (a) exemplars of symmetrical responding, and (b) all prerequisite discriminations among test samples and comparisons. After pigeons had learned two arbitrary-matching tasks (A-B and C-D), they were given a reinforced symmetry test for half of the baseline relations (B1-A1 and D1-C1). To control for the effects of reinforcement during testing, two novel, nonsymmetrical responses were concurrently reinforced using the other baseline stimuli (D2-A2 and B2-C2). Pigeons matched at chance on both types of relations, thus indicating no evidence for symmetry. These symmetrical and nonsymmetrical relations were then directly trained in order to provide exemplars of symmetry and all prerequisite discriminations for a second test. The symmetrical test relations were now B2-A2 and D2-C2 and the nonsymmetrical relations were D1-A1 and B1-C1. On this test, 1 pigeon showed clear evidence of symmetry, 2 pigeons showed weak evidence, and 1 pigeon showed no evidence. The previous training of all prerequisite discriminations among stimuli, and the within-subject control for testing with reinforcement seem to have set favorable conditions for the emergence of symmetry in nonhumans. However, the variability across subjects shows that methodological variables still remain to be controlled.     

Psychological essentialism and the differential attribution of uniquely human emotions to ingroups and outgroups

According to the psychological essentialism perspective, people tend to explain differences between groups by attributing them different essences. Given a pervasive ethnocentrism, this tendency implies that the human essence will be restricted to the ingroup whereas outgroups will receive a lesser degree of humanity. Therefore, it is argued that people attribute more uniquely human characteristics to the ingroup than to the outgroup. The present article focuses on secondary emotions that constitute such characteristics. Study 1 showed that members of high‐ and low‐status groups attribute more positive secondary emotions to the ingroup than to the outgroup. Study 2 verified that the differential attribution extended also to negative secondary emotions. No exemplars of emotions were provided in Study 3. Instead, participants had to estimate the means of two distributions of numbers that supposedly represented characteristics of the ingroup and of the outgroup. The results of this third experiment illustrated the reluctance to attribute secondary emotions to the outgroup. The findings are discussed from the perspective of psychological essentialism. Copyright © 2001 John Wiley & Sons, Ltd.     

Impact of low-level expression dermatological diseases on the quality of life as a function of its level of specificity

The impact of dermatological diseases on the quality of life is relatively well established, although some results do not support this relationship. Whereas a few studies indicate a decrease in various indicators of quality of life in conditions of disease, in other studies, this effect has not been observed. These differences can be explained by the use of different concepts of quality of life and/or the comparison of different severity levels of the diseases. The purpose of this paper is to analyze the impact of low-level expression dermatological diseases on various concepts of quality of life. Two hundred-ninety-nine participants completed a questionnaire about symptoms, psychological and psychosocial impact, and general and specific satisfaction. Results show that minor dermatological diseases affect health-related quality of life, but not quality of life considered as well-being.     

Examining the Impact of Training on the Homosexual Conduct Policy for Military Personnel

The impact of training related to the Don't Ask, Don't Tell, Don't Pursue policy on training outcomes of military personnel was examined with data from the Department of Defense Inspector General's Don't Ask, Don't Tell, Don't Pursue Policy Survey of military personnel (N = 71,570). We hypothesized that training related to the Don't Ask, Don't Tell, Don't Pursue policy would impact participant's reactions, learning and cognitive outcomes, and behavioral and organizational outcomes. Results indicate that individuals who reported having received training on the homosexual conduct policy perceived the policy to be more effective at preventing/reducing harassment; were more likely to feel free to report harassment complaints; reported greater levels of understating and were more knowledgeable of the policy; reported higher levels of intolerance of harassment; and reported that more actions had been take at their installation/ship to reduce and prevent harassment than individuals who had not received any training. Although the pattern of results was statistically significant, the magnitude of these effects were small (η ² = .001–.109). These findings highlight the continuing need to expand current efforts to reduce and curtail harassment based on perceived sexual orientation.