Emotions, personality, and health: introduction to the special issue

Our intent in this introduction to the special issue on Emotions, Personality, and Health is to alert readers to the logic underlying the editors' choices of topics for the issue and to provide a brief summary of its contents. We discuss how the 10 articles fit together to provide a mosaic of diverse approaches to the study of emotion. Collectively, these articles show ways that emotion research may be integrated with personality theory to inform us about the psychological dimensions of health and illness.     

Children's performance on a false-belief task is impaired by activation of an evolutionarily-canalized response system

We examine whether children's performance on a false-belief task is impaired by task content that activates an early-developing, prepotent motivational system: predator-avoidance. In two studies (N = 46 and N = 37), children aged 3-4 years completed variants of a false-belief task that involved predator-avoidance, playmate-avoidance, prey-seeking, and playmate-seeking, respectively. The proportion of correct answers on the playmate-avoidance task (Study 1: 52%; Study 2: 51%) was significantly greater than the proportion of correct answers on the analogous predator-avoidance task (Study 1: 28%; Study 2: 22%). This difference was not an artifact of children generally performing better on playmate stories than on predator-prey stories. The findings are consistent with the hypothesis that activation of the predator-avoidance system generates prepotent response patterns that pre-empt full consideration of the mental states of the prey characters in false-belief stories.     

Do expertise and the degree of perception-action coupling affect natural anticipatory performance?

Two experiments using a temporal occlusion paradigm (the first with expert and novice participants and the second with participants of intermediate skill) were conducted to examine the capability of tennis players to predict the direction of an opponent's service in situ. In both experiments two different response conditions, reflecting differing degrees of perception-action coupling, were employed. In a coupled condition players were required to make a movement-based response identical to that which they would use to hit a return of service in a game situation, whereas in an uncoupled condition a verbal prediction of service direction was required. Experiment 1 provided clear evidence of superior prediction accuracy under the coupled response condition when ball flight was available, plus some limited evidence to suggest that superior prediction accuracy under uncoupled response conditions might hold true if only advance (pre-contact) information was available. Experiment 2 showed the former finding to be a robust one, but was unable to reveal any support for the latter. Experiment 1 also revealed that expert superiority is more apparent for predictions made under natural (coupled) than uncoupled response-mode conditions. Collectively, these findings suggest that different perceptual processes may be in operation in anticipatory tasks which depend on skill level, the type of information presented, and degree of perception-action coupling inherent in the task requirements.     

Confirmatory factor analysis of the WMS-III in patients with temporal lobe epilepsy

Five competing models specifying the factor structure underlying the Wechsler Memory Scale-Third Edition (D. Wechsler, 1997b) primary subtest scores were evaluated in a sample of patients with intractable temporal lobe epilepsy (N = 254). Models specifying separate immediate and delayed constructs resulted in inadmissible parameter estimates and model specification error. There were negligible goodness-of-fit differences between a 3-factor model of working memory, auditory memory, and visual memory and a nested--more parsimonious--2-factor model of working memory and general memory. The results suggest that specifying a separate visual memory factor provides little advantage for this sample--an unexpected finding in a population with lateralized dysfunction, for which one might have predicted separate auditory and visual memory dimensions.     

Familiarisation with faces selectively enhances sensitivity to changes made to the eyes

Two experiments were designed to isolate the facial information utilised in the learning of new faces. In experiments 1 and 2, two groups of subjects were each trained on different groups of faces by means of a dynamic video presentation. They were then shown both trained and novel faces in a same-different decision task, where 'different' trials included manipulations of internal and external facial features, and the task was to decide whether two images were identical or had a difference in one or more features. Both experiments showed that hair change was most easily detected in untrained (unfamiliar) faces. When faces had been trained (familiar), detection of eye changes was selectively enhanced and sensitivity to hair changes was maintained. While previous studies have suggested that familiar face representations are weighted towards their internal features, our experimental results show that this is due to selective enhancement of sensitivity to changes made to the eyes alone, with no reduction in the salience of the hair. Moreover, within the limits of the familiarisation used here, there was no enhancement of the representation of the other internal face features examined.     

Hippocampal EEG and Unit Activity Responses to Modulation of Serotonergic Median Raphe Neurons in the Freely Behaving Rat

Hippocampal EEG, GABAergic interneurons, and principal cells were recorded simultaneously as rats foraged within one of three environments both before and after modulation of serotonergic inputs to the hippocampus. Median raphe microinjections of the 5-HT1a receptor agonist 8-OH-DPAT were made to produce inhibition of serotonergic neurons in this region. Such microinjections produced behavioral arousal and increases in the amplitude of hippocampal EEG theta. Consistent with the pattern of serotonergic innervation of the hippocampus, the GABAergic interneuron population was affected differentially by the microinjections. Principal cells were generally unaffected by the manipulation and maintained robust spatial firing correlates within the foraging environment. The results provide basic data on the relationship between serotonergic median raphe neurons and hippocampal activity in a behaving animal. The data suggest that behavioral responses to manipulation of the serotonergic system are mediated by brain regions other than the hippocampus or are mediated through changes in the activity of hippocampal interneurons.     

Gravity biases in a non-human primate?

Pre-school children expect falling objects to travel in a straight line even when there are clear physical mechanisms that deviate the object's path (Hood, 1995). The current study set out to determine whether this expectancy is limited to humans. Cotton-top tamarins (Saguinus oedipus oedipus), a New World monkey species, were tested on Hood's (1995) experimental task where objects are dropped down a chimney connected by an opaque tube to one of three containers. Like human children, there was a significant tendency to search in the container underneath the chimney where the food was dropped on the first trial, even though aligned chimneys and containers were never connected. These search errors suggest that there may be a gravity bias that operates when both primate species fail to understand the constraints operating on object trajectories. Unlike human children however, tamarins were generally more likely to perseverate in making errors even though repeated testing and cost incentives were used.     

The role of central and peripheral vision in postural control duringwalking

Three hypotheses have been proposed for the roles of central and peripheral vision in the perception and control of self-motion: (1) peripheral dominance, (2) retinal invariance, and (3) differential sensitivity to radial flow. We investigated postural responses to optic flow patterns presented at different retinal eccentricities during walking in two experiments. Oscillating displays of radial flow (0° driver direction), lamellar flow (90°), and intermediate flow (30°, 45°) patterns were presented at retinal eccentricities of 0°, 30°, 45°, 60°, or 90° to participants walking on a treadmill, while compensatory body sway was measured. In general, postural responses were directionally specific, of comparable amplitude, and strongly coupled to the display for all flow patterns at all retinal eccentricities. One intermediate flow pattern (45°) yielded a bias in sway direction that was consistent with triangulation errors in locating the focus of expansion from visible flow vectors. The results demonstrate functionally specific postural responses in both central and peripheral vision, contrary to the peripheral dominance and differential sensitivity hypotheses, but consistent with retinal invariance. This finding emphasizes the importance of optic flow structure for postural control regardless of the retinal locus of stimulation.