Distributed planning of movement sequences

Three experiments are reported that examine whether fast finger-tapping sequences are entirely planned before execution starts (advance planning), or if they can be started while planning is still under way (distributed planning). Subjects performed finger tapping sequences of three to eight taps at a high rate, under both simple and 2-choice reaction time (RT) conditions. The sequences differed in the location of an accentuated element within them. The RT to choose between sequences with different accent locations progressively decreased as an inverse function of the time-distance between the initial tap and the first point at which the alternative sequences differed. The shortening in choice reaction time (CRT) was never accompanied by noticeable changes in the inter-response times or force patterns of the tapping sequences. The RT to initiate sequences with accent location known beforehand (SRT condition) showed, in two of three experiments, a weak decreasing trend as the accentuated tap shifted away from the beginning of the sequence. The SRT results suggest a possible predominance of advance planning when the same sequence is repeated over a series of trials. The CRT results are taken as evidence that planning of the sequence beyond the unpredictable tap could be distributed before and after sequence initiation. Several factors are discussed that may influence the balance between planning in advance of, and planning in parallel with, sequence execution.     

Children's preference for challenge: the role of perceived competence and control

This research tested the hypothesis that children's perceptions of academic competence and their personal control over school-related performance affects subsequent intrinsic interest and preference for challenge in an evaluative setting. In a correlational study, children's self-reported perceptions of academic competence and personal control were found to relate positively to their intrinsic interest in schoolwork and preference for challenging school activities. A subset of this sample was exposed to varying levels of a controlling directive, and preference for challenge was assessed behaviorally during a free-choice period in which subjects were unaware that they were being observed. As predicted, the data indicated that when given the evaluative, controlling directive, children who had high perceptions of academic competence and control preferred a greater challenge than did children whose perceptions were low on these measures. No difference between groups in terms of preference for challenge was evident when no controlling directive was presented. These findings are discussed in terms of theories of intrinsic motivation and potential processes that underly these effects.     

Effects of Computer Privacy on Help-Seeking1

Subjects (N= 28) performing a complex disjunctive concept-formation task on a microcomputer were given the opportunity to seek help following failure to correctly identify concepts. The proportion of those seeking help was significantly greater when the source of help was the computer itself (86%) rather than another person (36%). Consistent with past research, those who did not ask for help gave reasons other than the potential negative social consequences of doing so. Self-report data and a systematic test for the presence of experimenter-induced demand ruled out several possible sources of confounding. The results have implications for designers of time-sharing and networked computer systems.     

Socializing Attribution: Generalization to “Real” Social Environments1

Social status variables have been shown to influence attributional judgments, but their effects have been demonstrated almost entirely in experimental settings. The influence of such statuses in experimental settings may differ from their influence in natural settings. We examined the influence on attributional judgments of the status characteristics of both subjects and actors in conjunction with variations in the degree of “real world” characteristics of both subjects and social context. These comparisons were drawn through a partial replication of earlier research investigating the effects of a social status variable, victim sex, and a situational variable—type of assault—on attributions about an assault victim. The social status characteristic, victim sex, had less influence on attributions in an adult juror sample than in a student sample and testimony-related characteristics were more influential in the adult juror sample than in the student sample. Thus, the categories of variables that influence attributions appear to depend on the context of judgment and on the breadth of subjects' life experience. These findings are discussed and we conclude with the caution that careful identification of the differences produced by context and subject characteristics is necessary to support generalization of laboratory-based research.     

Influence of positive affect on the subjective utility of gains and losses: it is just not worth the risk

A modification of the procedure originally used by Davidson, Suppes, and Siegel (1956) to measure subjective utility was used to study the influence of positive affect on individuals' perceived value (utility) functions. Results indicated, as expected, that persons in whom positive affect had been induced showed a more negative subjective utility for losses than did controls. This indicates that losses seem worse to people who are feeling happy than to those in a control condition. The subjective utility functions of the two groups did not differ as much, however, when people were considering potential gain. Thus, at least in the situation tested in this study, potential gains did not seem to be more appealing (nor less so) for affect subjects than they did for controls. These findings are discussed in relation to theoretical issues in decision making and work suggesting that positive affect can promote increased sensitivity to losses in situations of potential meaningful loss.     

The recognition of threatening facial stimuli

Two studies examined the information that defines a threatening facial display. The first study identified those facial characteristics that distinguish between representations of threatening and nonthreatening facial displays. Masks that presented either threatening or nonthreatening facial displays were obtained from a number of non-Western cultures and scored for the presence of those facial features that discriminated between such displays in the drawings of two American samples. Threatening masks contained a significantly higher number of these characteristics across all cultures examined. The second study determined whether the information provided by the facial display might be more primary nonrepresentational visual patterns than facial features with obvious denotative meaning (e.g., diagonal lines rather than downturned eyebrows). The subjective response to sets of diagonal, angular, and curvilinear visual stimuli revealed that the nonrepresentational features of angularity and diagonality in the visual stimulus appeared to have the ability to evoke the subjective responses that convey the meaning of threat.     

The role of visual information in control of a constrained locomotor task

The nature of visually guided locomotion was examined in an experiment where subjects had to walk to targets under various conditions. Target distance was manipulated so that subjects had to (a) lengthen their paces in order to hit the target; (b) shorten their paces; (c) make no adjustments to their standard pace length at all. They did this under four visual conditions: (a) normal vision; (b) with vision restricted to a "snapshot" each time the foot that was to be placed on the target was on the ground; (c) with a snapshot each time the foot to be placed was in the swing phase; and (d) no vision after departure fro the target. The results show that the subjects succeed in reaching the target in most cases. However, the smoothness and fluidity of their movements vary significantly between conditions. Under normal vision or where visual snapshots are delivered when the pointing foot is on the ground, locomotion is smoothly regulated as the subjects approach the target. where snapshots are delivered when the pointing foot is in the swing phase, regulation becomes clumsy and ill coordinated. Where no vision is available at all during the approach, adjustments are made, but these are least coordinated of all. The results show that well-coordinated visual regulation does not require continuous visual guidance but depends on intermittent information being available at the appropriate times in the action sequence. Such timing is often more important than the total amount of information that is available for guidance.