Motor adaptation to different dynamic environments is facilitated by indicative context stimuli

When humans are exposed to external forces while performing arm movements, they adapt by compensating for these novel forces. The basis of this learning process is thought to be a neural representation that models the relation between all forces acting upon the system and the kinematic effects they produce, called inverse dynamic model (IDM). The present study investigated whether and how the predictability of a given external force affects the selection of an appropriate motor response to compensate for such force. Adult human subjects (N=32) held a handle that could rotate around the elbow joint and learned to perform goal-directed forearm flexion movements, while an external velocity-dependent negative damping force was applied that assisted forearm movement. Subjects were randomly assigned to two groups. In the associative group, the applied damping force was always associated with a specific initial position. Thus, after initial learning, the force application became predictable. In the non-associative group, where the same movements were performed, the applied force was independent of the initial position, so that no association between force and location could be formed. We found that only the associative group significantly reduced target error when damping was present. That is, the location cue aided these subjects in generating dynamic responses in the appropriate limb. Our results indicate that motor adaptation to different dynamic environments can be facilitated by indicative stimuli.     

Acquisition and use of mental operators: the influence of natural order of events

The present article reports two experiments investigating the influence of natural order of events on the acquisition and use of knowledge about operations, in short mental operators. The principle of use specificity states that task performance depends directly on the similarity between acquisition context and the present situation. In contrast, the principle of natural order proposes that knowledge about operations can always be applied easier (faster) if reasoning follows the natural order of events. In Experiment 1, participants had to apply alphabet-arithmetic operators and LISP functions in a prognosis task (A + 2 = ?) or a retrognosis task (? - 2 = A). In alphabet-arithmetic, an advantage for the first kind of task at the beginning of training decreased with increasing practice. In LISP, however, a preference for this task (corresponding with a prospective knowledge use) emerged with increasing practice. In Experiment 2, arithmetic relations between digit pairs had to be induced. In a causal context condition, relations were described as input and output of electric circuits, in a neutral context the relations were described as arithmetic dependencies. A preference for the prognosis task was found for the causal context condition (corresponding with a prospective knowledge use) but not for the neutral one. The findings suggest that the natural order of events moderates the acquisition and use of mental operators. Further research is required to clarify the bases for this moderation.     

Self-esteem, academic self-concept, and achievement: how the learning environment moderates the dynamics of self-concept

The authors examine the directionality of effects between global self-esteem, domain-specific academic self-concepts, and academic achievement. Special emphasis is placed on learning environments as potential moderators of the direction of these effects. According to the meritocracy principle presented here, so-called bottom-up effects (i.e., self-esteem is influenced by academic self-concept) are more pronounced in meritocratic learning environments than in ego-protective learning environments. This hypothesis was examined using a three-wave cross-lagged panel design with a large sample of 7th graders from East and West Germany, a total of 5,648 students who were tested shortly after German reunification. Reciprocal effects were found between self-esteem, academic self-concept, and academic achievement. In conformance with the meritocracy principle, support for bottom-up effects was stronger in the meritocratic learning environment.     

Social norms and the likelihood of raping: Perceived rape myth acceptance of others affects men's rape proclivity

Research showing that rape myth acceptance (RMA) causally affects rape proclivity (RP) was extended by examining the impact of RMA-related norms on RP. Male students (total N = 264) received feedback about the alleged responses of other students to RMA items either before (Experiment 1) or after (Experiment 2) they reported their own RMA, and then their RP was assessed using acquaintance-rape scenarios. The level of RMA feedback was varied. Results showed that higher norms led to higher RP. In Experiment 1, this effect was mediated via self-reported RMA. Experiment 2 yielded main effects of both RMA feedback and self-reported RMA and an interaction effect showing that RMA feedback was particularly influential at higher levels of own RMA. Theoretical and practical implications of these findings are discussed.     

Suppression of EEG gamma activity may cause the attentional blink

The attentional blink (AB) is an impairment of attention, which occurs when subjects have to report a target stimulus (T2) following a previous target (T1) with a short delay (up to 600 ms). Theories explaining the AB assume that processing of T2 is more vulnerable to decay or substitution, as long as attention is allocated to T1. Existing models of the AB, however, do not account for the fact that T2 detection accuracy reaches the minimum when T2 is presented after about 300 ms and not immediately following T1. Therefore, a new model is suggested, which is based on chronometrical considerations together with recent neurophysiological findings concerning the relation between the P3 event-related potential and the AB, the interaction between P3 and gamma oscillations, and the significance of the early evoked gamma band response. We hypothesize that suppression of the early gamma response to T2, accompanying the P3 related to T1, causes the AB.     

Process-dissociation procedure: a testable model for considering assumptions about the stochastic relation between consciously controlled and automatic processes

This paper presents an extension of the process-dissociation procedure with wordstem completion, which makes possible the measurement of the stochastic relationship between consciously controlled and automatic processes. By means of an indirect wordstem completion test, the conditional probabilities of conscious remembering with and without automatic processes can be successfully determined. A multinomial model for the evaluation of this extended process-dissociation procedure is presented. This model makes the distinction between voluntary and involuntary conscious memory processes possible and has been applied to two experiments discussed in this paper. The results show that the assumption of stochastic independence is often violated, albeit not as strongly as predicted by the redundancy or exclusivity model variants. Two conscious processes were found, voluntary and involuntary conscious memory processes, each with a different probability of occurrence.     

Speaker variations influence speechreading speed for dynamic faces

We investigated the influence of task-irrelevant speaker variations on speechreading performance. In three experiments with video digitised faces presented either in dynamic, static-sequential, or static mode, participants performed speeded classifications on vowel utterances (German vowels /u/ and /i/). A Garner interference paradigm was used, in which speaker identity was task-irrelevant but could be either correlated, constant, or orthogonal to the vowel uttered. Reaction times for facial speech classifications were slowed by task-irrelevant speaker variations for dynamic stimuli. The results are discussed with reference to distributed models of face perception (Haxby et al, 2000 Trends in Cognitive Sciences 4 223-233) and the relevance of both dynamic information and speaker characteristics for speechreading.     

The motivational bases of right-wing authoritarianism and social dominance orientation: relations to values and attitudes in the aftermath of September 11, 2001

Research suggests that different motivational dynamics underlie right-wing authoritarianism (RWA) and social dominance orientation (SDO). These differences may be framed in the theory of basic human values. RWA may trace back to conservation versus openness-to-change values, and SDO to self-enhancement versus self-transcendence values. Based on a large-scale German survey, associations of RWA and SDO with personal values and attitudes in the aftermath of September 11, 2001, were analyzed. Results indicated that RWA related more strongly than SDO to conservation values and threat-related attitudes toward Islam as an expression of the motivational goals of social control and security, whereas RWA and SDO related equally to self-enhancement versus self-transcendence values and concern for negative consequences of military action as an expression of the motivational goal of altruistic concern. Thus, the motivational bases of RWA and SDO appear to be only partly different.     

Synergistic person x situation interaction in distributive justice behavior

A person x situation interaction is synergistic when a personality trait amplifies the effect of a situational factor. The present study tested how individuals' justice attitudes and situational factors jointly affect the allocation of financial burdens. Six insurance cases were described to 80 participants. Economic status of client (high, low) and responsibility of client for damage of the insured (high, low) were manipulated between subjects. Participants suggested a percentage of the total costs that they considered a fair contribution by the client. In accordance with the synergistic model, justice attitude (person factor) and responsibility for damage (situation factor) interacted and explained 5% of the variance of the dependent variable. With increasing negativity of attitude toward equality, the effect of responsibility was larger. Several cognitive mechanisms, such as motivated perception, selective attention, and the availability of attitude congruent situation schemas, that may account for synergistic interactions in justice behavior and in other domains were discussed.     

Ruminative thought and the deactivation of an intention

When do individuals manage to disengage from intentions, when do they fail to do so? It is suggested that a major reason for a failure to disengage lies in a postactional evaluation that goes astray. This is especially likely if the context does not provide cues for other activities. Cues from another activity waiting to be enacted should induce a pressure to terminate the evaluation of the performance of the past activity. They should focus this evaluation on an analysis of elements of the performance rather than self evaluation. If the focus is on self-evaluation, the susceptibility for ruminative thinking increases. In an experiment to test these assumptions, subjects (N=53) worked on an intelligence test task. Half the subjects received failure feedback on all six problems of this task. The other half received no failure feedback. Subjects’ thoughts during a waiting period following the intelligence test task were assessed. Before the beginning of the waiting period, half the subjects received cues for another test to follow. The data supported the hypothesis that cues for a new activity help subjects to stop thinking about the first task. Without cues, subjects were susceptible to falling into self-evaluation loops. In this case, subjects were unable to remove the past task from their minds until the end of the waiting period. With cues, the postactional evaluation became task-centered, promoting a disengagement from the past task.