Spatial and temporal adaptations that accompany increasing catching performance during learning

The authors studied changes in performance and kinematics during the acquisition of a 1-handed catch. Participants were 8 women who took an intensive 2-week training program during which they evolved from poor catchers to subexpert catchers. An increased temporal consistency, shift in spatial location of ball-hand contact away from the body, and higher peak velocity of the transport of the hand toward the ball accompanied their improvement in catching performance. Moreover, novice catchers first adjusted spatial characteristics of the catch to the task constraints and fine-tuned temporal features only later during learning. A principal components analysis on a large set of kinematic variables indicated that a successful catch depends on (a) forward displacement of the hand and (b) the dynamics of the hand closure, thereby providing a kinematic underpinning for the traditional transport-manipulation dissociation in the grasping and catching literature.     

Differential testosterone secretory capacity of the testes of aggressive and nonaggressive house mice during ontogeny

In this study, testosterone secretory capacity of testicular Leydig cells during ontogeny was determined in males of an aggressive and a nonaggressive genetic selection line of wild house mice. Neonates, 23-day-old prepubertals, and adult male mice were studied. A morphometric method was used to quantify 3β-hydroxy steroid dehydrogenase (3β-3HSD)-stained Leydig cells in testicular sections to determine testosterone secretory capacity. We consider this parameter to reflect circulating testosterone in the plasma. The results of this study show that the testosterone secretory capacity of Leydig cells in the testis changes differentially during development in males of the aggressive and nonaggressive selection lines. This capacity is highest in the aggressive selection line males at adulthood and at the prepubertal age of 23 days. Surprisingly, at birth, the highest T-secretory capacity was observed in the males of the nonaggressive selection line. The significance of an interaction between genetic factors and differences in perinatal testosterone for the individual variation in adult aggressive behavior is discussed.     

Pre-extinction of sensory preconditioned electrodermal activity

In the present study, sensory preconditioning of human electrodermal activity was demonstrated. In the first phase of the experiment, two pairs of neutral pictures of human faces were presented (A/B and C/D) sequentially. In the second phase, one picture of one pair was immediately followed by an electrocutaneous stimulus (B+), and one picture of the other pair was not (D-). In the third phase the other picture of each pair (A and C) was tested. The effect of A and C alone presentations (pre-extinction) between the first and the second phase was investigated. When only those participants that showed reliable B+/D- differentiation were considered, the extinction group did not show stronger conditioned electrodermal activity to A than to C, whereas the control group did. These findings suggest that sensory preconditioning of anticipatory/preparatory responding only occurs when the pre-conditioned stimulus (A) actually predicts the conditioned stimulus (B).     

Longitudinal links between childhood peer acceptance and the neural correlates of sharing

Childhood peer acceptance is associated with high levels of prosocial behavior and advanced perspective taking skills. Yet, the neurobiological mechanisms underlying these associations have not been studied. This functional magnetic resonance imaging study examined the neural correlates of sharing decisions in a group of adolescents who had a stable accepted status (n = 27) and a group who had a chronic rejected status (n = 19) across six elementary school grades. Both groups of adolescents played three allocation games in which they could share money with strangers with varying costs and profits to them and the other person. Stably accepted adolescents were more likely to share their money with unknown others than chronically rejected adolescents when sharing was not costly. Neuroimaging analyses showed that stably accepted adolescents, compared to chronically rejected adolescents, exhibited higher levels of activation in the temporo‐parietal junction, posterior superior temporal sulcus, temporal pole, pre‐supplementary motor area, and anterior insula during costly sharing decisions. These findings demonstrate that stable peer acceptance across childhood is associated with heightened activity in brain regions previously linked to perspective taking and the detection of social norm violations during adolescence, and thereby provide insight into processes underlying the widely established links between peer acceptance and prosocial behavior.     

On the role of beliefs in observational flavor conditioning

In previous research (Baeyens, Vansteenwegen et al., 1996) we demonstrated that when observers consume a series of CS+ and CS−flavored drinks while simultaneously watching a videotaped model who synchronically drinks identical drinks and facially expresses his evaluation (dislike to CS+, neutral to CS−) of the liquids, the observers acquire a dislike for CS+ flavored relative to CS−flavored drinks. The aim of the present experiments was to test some predictions derived from a “direct conditioning” theory of such observational flavor learning. Using the same observational flavor conditioning procedure, we investigated (Exp. 1) the effect of manipulating the observers’ belief concerning the relationship between the drinks that they and the model were consuming (same/different/no information). Observational flavor conditioning was obtained when observers were led to believe that they were drinking the same drinks as the model did, and when they were not informed about this relationship, but not when told to be drinking different drinks. At the same time, however, the observers were not able to correctly identify the source of the model’s expression of dislike: They showed no CS-US contingency-awareness. Whereas the former finding suggests the causal involvement of conscious beliefs and cognitive inference processes in observational learning, the latter is more in line with the idea that the model’s facial expressions may act like a US’ which is automatically associated with the paired flavor CS+, without any involvement of conscious beliefs or cognitive inferences. These two crucial findings were replicated in Exp. 2. Also, we obtained evidence in this study that the belief manipulation affected learning through its influence on the observers’ attention for the model’s facial evaluative expressions. These results can be integrated either by a cognitive theory allowing the beliefs on which the inferences are based to be of an implicit nature, or by a “direct conditioning” theory that conceives of the US’ as an interpreted event, rather than as a mechanistically and invariantly acting physical entity.     

Changing patterns of infant behavior and mother–infant interaction: Intra- and interindividual variability

Mother–infant dyads were observed weekly at their homes for a 15-month period. In this way longitudinal data about the infants’ crying, fretting/fussing, smiling and different types of physical contact with the mother were collected. The subject of this study concerns the variability and stability in macroscopic patterns of associations between these behaviors. Different types of associations were found between the behaviors, and most of them changed considerably as the infant developed. Individual differences in the nature of the associations and in the changes they underwent over time predominated, but in a limited number of cases the infants shared the same developmental trajectories of behavioral associations. The results show how the use of intensive time series designs can be advantageous in clarifying issues of long-term variability and stability in human behavior. They also support the notion of changing patterns of behavior being a normal feature of early development.     

No transfer of calibration between action and perception in learning a golf putting task

We assessed calibration of perception and action in the context of a golf putting task. Previous research has shown that right-handed novice golfers make rightward errors both in the perception of the perfect aiming line from the ball to the hole and in the putting action. Right-handed experts, however, produce accurate putting actions but tend to make leftward errors in perception. In two experiments, we examined whether these skill-related differences in directional error reflect transfer of calibration from action to perception. In the main experiment, three groups of right-handed novice participants followed a pretest, practice, posttest, retention test design. During the tests, directional error for the putting action and the perception of the perfect aiming line were determined. During practice, participants were provided only with verbal outcome feedback about directional error; one group trained perception and the second trained action, whereas the third group did not practice. Practice led to a relatively permanent annihilation of directional error, but these improvements in accuracy were specific to the trained task. Hence, no transfer of calibration occurred between perception and action. The findings are discussed within the two-visual-system model for perception and action, and implications for perceptual learning in action are raised.     

The attentional blink is diminished for targets that form coherent semantic categories

Studies have shown that the attentional blink (AB) effect is diminished for intrinsically salient T2 stimuli, such as arousing, familiar, personally relevant words, or stimuli with salient low-level visual features. We examined whether the AB is diminished also for stimuli that do not have special inherent properties but are made salient by the context. One such contextual factor is the coherence of the T2 stimulus set. In three experiments, we found that the AB is diminished for stimuli that form a coherent semantic category within the T2 stimulus set. Both theoretical and practical implications are discussed.     

An experimental approach towards the evaluation of a seat belt campaign with an inside view on the psychology behind seat belt use

A Belgian national safety belt campaign was evaluated by means of a questionnaire survey in an adolescent sample. The evaluation was done through a three group after-only design with the use of one control group and two experimental groups. The first experimental group, the attentive group, was exposed to the campaign material in a very direct, attentive way, whereas the second experimental group, the pre-attentive group, was exposed rather inattentively. The framework of the Theory of Planned Behaviour (TPB) was applied and extended with a habit and a past behaviour variable in order to verify whether seat belt usage is to be understood as an automaticity mechanism (i.e., habitual or repeated past behaviour) or as planned behaviour. In terms of campaign effect, the comparison of the pre-attentive group and the control group revealed no significant differences. However, the attentive group and the control group differed significantly regarding two basic dimensions of perceived behavioural control (i.e., confidence and motivation), habit, past behaviour, behavioural intention and behaviour. In terms of explaining seat belt usage, linear regression models were fitted and gave most support for the repeated past behaviour approach. According to the latter, using seat belts is recycling an originally reasoned behaviour, yet without systematically going through the whole underlying reasoning every time a situation in which the decision to wear a seat belt (or not) presents itself. The practical implications of these findings are discussed more in detail.