Understanding the language of reasoning: Cognitive,linguistic, and developmental influences

Certain linguistic structures imply speakers' beliefs about their utterances. Factuals imply that the speaker's hypothesis matches observed data; counterfactuals suggest that hypotheses and observations differ, and uncertainty implies that unclear observations make many hypotheses tenable. We examined how age(11-and 16-year-olds and college students) and syntactic structure (subordinating conjunctions, cognitive verbs, and verb modifications) affect the ability to specify the hypothetical and observational referents of expressions of factual, counterfactual, and uncertainty beliefs. There was considerable linguistic growth during adolescence. College students outperformed the younger students. Age differences were most pronounced on judging the hypothetical referents of counterfactuals and uncertainty structures. The two precollege groups often misinterpreted counterfactuals and uncertainty structures because they equated hypotheses with observations. They seldom understood that uncertainty meant that more than one hypothesis could account for observations. Verb modifications were easier to interpret than cognitive verbs, and subordinating conjunctions were hardest. Factuals were easier than counterfactuals and uncertainty structures.     

On the hand transport component of prehensile movements

Jeannerod (1981) proposed that prehensile movements involve two independent visuomotor channels that are responsible for hand transport and hand aperture. In many studies, the movement of a marker placed on the wrist has been used as an index of hand transport because wrist movement is unaffected by the movements of the digits responsible for hand aperture. In the present study, the spatial paths of the wrist, index finger, and thumb of 5 adults, each performing 50 reaching movements, were measured with a WATSMART movement tracking system, and their variability was analyzed. The measures of movement variability suggest that the motor system is more concerned with thumb position than with wrist position during hand transport. Although the wrist is a technically convenient index of hand transport, the thumb may be a more appropriate index from the point of view of motor control     

Effects of surface texture and grip force on the discrimination of hand-held loads

In this paper, we report the results from two experiments in which subjects were required to discriminate horizontal load forces applied to a manipulandum held with a precision grip. The roughness (and hence friction) of the grip surfaces and required grip force were manipulated. In the first experiment, subjects were instructed to judge the load while maintaining hand position and not letting the manipulandum slip. It was found that performance was influenced by surface texture; a given load was judged to be greater when the surface texture was smooth than when it was rough. This result is consistent with a previous study based on lifting objects and indicates that the effect of surface texture applies to loads in general and not just to gravitational loads (i.e., weight). To test whether the load acting on a smooth object is judged to be greater because the grip force required to prevent it from slipping is larger, a second experiment was carried out. Subjects used a visual feedback display to maintain the same grip force for smooth and rough manipulandum surfaces. In this case, there was no effect of surface texture on load perception. These results provide evidence that perceived load depends on the grip force used to resist the load. The implications of these results in terms of central and peripheral factors underlying load discrimination are considered.     

Response delays and the timing of discrete motor responses

A model for the timing of repetitive discrete motor responses is proposed, and a prediction of negative dependency between successive interresponse intervals is confirmed by data from a Morse key tapping task. A method that makes use of the first-order serial correlation between interresponse intervals is used to distinguish between variance due to a timekeeping process and variance in motor response delays subsequent to the timekeeper. These two quantities are examined as a function of mean interresponse interval.     

A qualitative understanding of reflective-teams II: Therapists' perspectives

A research team developed and asked questions to a reflective-team about their clinical practice. The purpose of the questions was to better understand reflective-team members' experiences, beliefs, and aspirations. A participant/observation methodology was used in formulating the questions to the therapists. Therapists stated that reflective-teams were valuable in resolving impasses, developing multiple perspectives on clients' problems, and encouraging interaction among team members, but were problematic if clients were unaccustomed to team practice or if there were physically too many people in the interviewing room. Therapists believed that reflective-teams as a team practice was not practical in typical practice settings.     

Facial and autonomic manifestations of the dimensional structure of emotion

While subjects viewed and rated a series of 25 emotionally evocative slides, their heart rate and skin conductance were continuously monitored and their facial expressions were covertly videotaped. Judges subsequently viewed the videotapes and rated trial-by-trial the pleasantness and intensity of each subject's facial expressions. Both phasic skin conductance responding and judged facial intensity were curvilinearly related to self-reported pleasantness, with the largest responses occurring at both extremes of the self-report scale. In contrast, phasic cardiac reactions and judged facial pleasantness were linearly related to self-reported pleasantness; extreme pleasantness was accompanied by heart rate acceleration, and unpleasantness by cardiac deceleration. The results suggest that visceral information reflects the dimensions that underlie the organization of affects and, hence, may play a more important role in emotional experience than is assumed in a number of currently held theories of emotion.