Effect of reaction time condition on EMG activities of the biceps brachii muscle in elbow flexion and forearm supination

Under simple- and choice-RT conditions, the biceps brachii muscle was examined in 8 healthy male subjects to determine how the temporal and spatial characteristics of elbow flexion and forearm supination differed at the initial phase of EMG activity and whether preparation or the presence of response uncertainty influenced the EMG outputs of the two movements. In the simple-RT condition, RT of supination was significantly faster than that of flexion but EMG activity of supination was less than that of flexion. In contrast, in the choice-RT condition, RT of flexion was significantly faster than that of supination but EMG activity of flexion was significantly reduced compared to supination. These findings indicate that advanced preparation or motor set facilitates the differentiation of RTs and EMG activities of the response movements and that response uncertainty causes a significant change in the temporal and spatial specificity of both elbow flexion and forearm supination.     

Ambiguity and rationality

Recently, several theories of decision making and probability judgment have been proposed that take into account ambiguity (Einhorn and Hogarth, 1985; Gardenfors and Sahlin, 1982). However, none of these theories explains exactly what the psychological causes of ambiguity are or addresses the issue of whether ambiguity effects are rational. In this paper, we define ambiguity as the subjective experience of missing information relevant to a prediction. We show how this definition can explain why ambiguity affects decisions in the ways it does. We argue that there are a variety of rational reasons ambiguity affects probability judgments and choices in the ways it does. However, we argue that the ambiguity effect does not cast doubt on the claim that utility theory is a standard of rational choice. Rather, we suggest that the effect of ambiguity on decisions highlights the fact that utility theory, like any normative model of decision making only prescribes the optimal decision, given what one knows.     

Contemporary theories of group psychotherapy: a systems approach to the group-as-a-whole.

The author discusses how subgroups represent the basic focus of the systems-centered group therapist. Particular attention is given to boundary issues and to how therapy takes place by facilitating the process of discriminating, communicating, and integrating perception of differences in the apparently similar and similarities in the seemingly different. Communication occurs at the boundaries between systems at all levels of the hierarchy: the group, the subgroup, and its members. Clinical vignettes are provided to illustrate important process issues, such as work with difficult patients, levels of intervention, and group resistance and defense.     

Declines in Major League Batting Performance as a Function of Game Pressure: A Drive Theory Analysis1

Zajonc's (1965) drive theory explanation argues that greater arousal tends to impair performance on difficult tasks. The hypothesis that arousal generated by “pressure situations” during major league baseball games would hinder batting performance—a difficult task—was tested by examining such performance during the 1989 season. Six “pressure situations” were identified, some occurring during the late innings of close games and others occurring throughout the game when there were two outs. Two measures of batting performance (batting average and slugging average) were employed. Results indicated broad support for the hypothesis. Reasons for this pattern are discussed, as are possible alternative explanations for these findings.     

Postural requirements and progression velocity in young walkers

This article describes developmental changes in gait velocity and relates these changes to gait parameters that index postural stability (step width and lateral acceleration) and two components of velocity (cadence and step length). Five children were observed longitudinally over a 2-year period after onset of independent walking. Their range of speed increased threefold in the first 6 months of independent walking and then remained constant. In contrast, step width decreased approximately twofold. Whereas in adults, cadence and step length contribute approximately equally to speed, when infants first begin to walk independently, increase in velocity is due mostly to increased step length. After 5 months of independent walking, the pattern reverses, and increase in velocity is due primarily to increased cadence. The pattern remains constant over the next 18 months. From a developmental point of view, the data lead us to interpret early walking (the first 5 months) as a process of integration of postural constraints into the dynamic necessities of gait movement. A second phase, beginning after 4 to 5 months of independent walking, is considered to be a tuning phase characterized by a more precise adjustment of the gait parameters.     

Controlling the uncontrollable: effects of stress on illusory perceptions of controllability.

Individuals' failure to exercise actual control over an event might be compensated for by trying to bolster a generalized, subjective sense of control. Control might then be sought by undertaking acts the effect of which on the environment is illusory. This observation led to the hypothesis that stress, which undermines persons' sense of control, would engender illusory perceptions of controllability. The hypothesis was tested in 3 experiments that required Ss to choose between 2 gambling forms. Although the 2 forms were essentially identical, 1 was designed to instill an illusion of control. The results showed that highly stressed Ss, compared with those who experienced low stress, preferred gambling forms that heightened perceptions of controllability.     

A study of the comparative structure of guilt and shame in a Chinese society.

On the basis of previous theoretical and empirical analyses of the comparative structures of guilt and shame, the authors hypothesized that antecedent condition (personal inadequacy vs. moral norm violation), audience presence, and personal responsibility attribution would distinguish shame from guilt. Although the subject population was Hong Kong Chinese, evidence from previous studies suggests that the comparative structures of guilt and shame are quite similar across cultures. The subjects were asked to recall either a guilt or a shame incident, and their responses were then coded into the predictor variables. The results of the study indicated that guilt was most likely to emerge when individuals had violated a moral norm and held themselves responsible for their conduct. In contrast, shame emerged more frequently when subjects felt personally inadequate than when they had violated moral norms. Moreover, when a guilt incident was reported, and audience was rarely mentioned, whereas subjects who reported a shame incident would generally feel personally responsible and often mentioned being looked at or evaluated. However, neither personal responsibility nor the presence of an audience seemed to be essential for a person to experience shame.     

Search behavior in various breeds of adult dogs (Canis familiaris): object permanence and olfactory cues.

Human analog tests of object permanence were administered to various breeds of adult dogs (Canis familiaris). Experiment 1 showed that the performance of terriers, sporting, and working dogs did not differ. Dogs succeeded in solving invisible displacement problems, but performance was lower than in visible displacement tests. Familiarity with the task had some influence because invisible displacement tests were more successful if they were preceded by visible displacement tests. In Experiment 2, odor cues from the target object and the hiding screens were available or were masked. Results confirmed that success was lower in invisible than in visible displacement tests and that these problems were solved on the basis of representation of visual information rather than on the basis of olfactory cues or of local rule learning. Dogs are compared with other species that display Stage 6 object permanence.     

The Chancellor's memory: Rhetoric and truth in discursive remembering

This paper explores the notion of truthfulness in research on conversational remembering. It argues that people's accounts of past events, before they can be taken as data on the cognitive workings of memory, need to be examined as contextualized and variable productions that perform pragmatic and rhetorical work; no one version can be taken as a person's real memory. The consequences of this discourse-analytical perspective are examined first through a critical discussion of Ulric Neisser's study of John Dean's testimony to the senate ‘Watergate’ committee. The issues are then explored more deeply in an analysis of reportings of a different event, in which similar (Watergate-like) issues of memory, truth and accuracy are also at issue. It is argued that: (a) all of Neisser's three kinds of memory–verbatim, gist and ‘repisodic’–involve problematical assumptions concerning their relation to some true, original event; and (b) that Dean's accounts of his memory and his displays of memory should be approached as occasioned productions oriented pragmatically to the assignment of guilt and avoidance of scapegoating. Through an analysis of newspaper reports (based on memory) of a controversial briefing given by the then British Chancellor of the Exchequer, Nigel Lawson, we then examine: (a) how discourse about what could be used as an arbiter of truth was rhetorically organized; (b) how participants' versions of events were constructed rhetorically, as parts of arguments; (c) that both sides in the dispute maintained the coherence of their positions by a form of error accounting similar to that used by Neisser with respect to Dean. It is suggested that cognitive psychologists, whether working in the laboratory or attempting to do real-world studies of everyday remembering, need to avoid simplistic notions of true original events, and can do so by addressing the rhetorical organization of participants' memory accounts.