The effects of temporal-precision and time-minimization constraints on the spatial and temporal accuracy of aimed hand movements

Discrete aimed hand movements, made by subjects given temporal-accuracy and time-minimization task instructions, were compared. Movements in the temporal-accuracy task were made to a point target with a goal movement time of 400 ms. A circular target then was manufactured that incorporated the measured spatial errors from the temporal-accuracy task, and subjects attempted to contact the target with a minimum movement time and without missing the circular target (time-minimization task instructions). This procedure resulted in equal movement amplitude and approximately equal spatial accuracy for the two task instructions. Movements under the time-minimization instructions were completed rapidly (M = 307 ms) without target misses, and tended to be made up of two submovements. In contrast, movements under temporal-accuracy instructions were made more slowly (M = 397 ms), matching the goal movement time, and were typically characterized by a single submovement. These data support the hypothesis that movement times, at a fixed movement amplitude versus target width ratio, decrease as the number of submovements increases, and that movements produced under temporal-accuracy and time-minimization have different control characteristics. These control differences are related to the linear and logarithmic speed-accuracy relations observed for temporal-accuracy and time-minimization tasks, respectively.     

Celtic culture,Calvinism, social and mental health on the Island of Lewis

The five points of federal Calvinism, as outlined by the Synod of Dort, have had a strong influence on the Protestant church. Their negative effects on the culture and society of the Western Isles of Scotland are often overlooked, or simply accepted as an expresion of that culture. In this paper, an attempt is made to show how Celtic culture on the Isle of Lewis has been held back by this theology, and the effect of this repression on society and the individual. Particular areas of concern are the neglect of the Gaelic language, and the incidence of violence, alcoholism, and depression. Iain Macritchie, S.T.M., comes from the village of Ballantrushal on the Island of Lewis. He is a Church of Scotland minister with a particular interest in training ministers for work in the Highlands and Islands of Scotland, to which he has returned after a year on the Scottish Fellowship at Union Theological Seminary.     

The role of neuroimaging in the discovery of processing stages a review

In this contribution we show how neuroimaging methods can augment behavioural methods to discover processing stages. Event Related Brain Potentials (ERPs), Brain Electrical Source Analysis (BESA) and regional changes in cerebral blood flow (rCBF) do not necessarily require behavioural responses. With the aid of rCBF we are able to discover several cortical and subcortical brain systems (processors) active in selective attention and memory search tasks. BESA describes cortical activity with high temporal resolution in terms of a limited number of neural generators within these brain systems. The combination of behavioural methods and neuroimaging provides a picture of the functional architecture of the brain. The review is organized around three processors: the Visual, Cognitive and Manual Motor Processors.     

Child abuse and neglect by parents with disabilities: A tale of two families

Two families, in which the children had been placed in foster care due to abuse and neglect by parents who had disabilities, were studied. In the first case, the mother was instructed in skills that our assessment suggested were important for her child's survival. The mother readily acquired and applied these skills, a fact reflected both in changes in her behavior and in changes in the child's well-being. In the second case, the parent's incremental resumption of child custody was made contingent upon completion of relevant parenting tasks. Initially, improvements in the completion of such tasks were evident, but over time and with the onset of militating factors, no further progress was made and all parental rights were terminated. The implications of these cases for behavior analysis and the effort to reunite and preserve families are discussed.     

Personological evaluation of Clance's Imposter Phenomenon Scale in a Korean sample

The purpose of this study was both to determine if the Impostor Phenomenon (IP) can be reliably and validly assessed in a Korean context and if so, evaluate the construct within the context of Jungian typology and the 5-factor model of personality. A sample of 654 Korean men and women were selected from 4 major Korean cities and administered the Clance Impostor Phenomenon Scale (CIPS; Clance & Imes, 1978) along with the Myers-Briggs Type Indicator (MBTI, Form G; Myers & McCaulley, 1985) and NEO Personality Inventory-Revised (NEO-PI-R; Costa & McCrae, 1992). Results indicated that the CIPS was very reliable, and the pattern of correlates suggested impostors to be introverted types on the MBTI. Results with the NEO-PI-R showed impostors to be very high on neuroticism and low on conscientiousness. This pattern of correlates is similar to other performance-inhibiting constructs such as fear of success and fear of failure. It was argued that IP be construed more as a motivational style than as a distinct clinical syndrome. The IP seems to be less pervasive in Korea than America and these cross-cultural implications were discussed.     

Biasing the pacemaker in the behavioral theory of timing

In the behavioral theory of timing, pacemaker rate is determined by overall rate of reinforcement. A two-alternative free-operant psychophysical procedure was employed to investigate whether pacemaker period was also sensitive to the differential rate of reinforcement. Responding on a left key during the first 25 s and on a right key during the second 25 s of a 50-s trial was reinforced at variable intervals, and variable-interval schedule values during the two halves of the trials were varied systematically. Responding on the right key during the first 25 s and on the left key during the second 25 s was not reinforced. Estimates of pacemaker period were derived from fits of a function predicted by the behavioral theory of timing to right-key response proportions in consecutive 5-s bins of the 50-s trial. Estimates of pacemaker period were shortest when the differential reinforcer rate most strongly favored right-key responses, and were longest when the differential reinforcer rate most strongly favored left-key responses. The results were consistent with the conclusion that pacemaker rate is influenced by relative reinforcer rate.     

Distinguishing Context Effects From Context Errors in Judgments of Behavior1

Context effects (assimilation and contrast) are examined in relation to accuracy in judgments of stimuli. Context effects are distinguished from context errors. This is shown to depend on one's definition of true scores, rater tendencies (leniency-severity) relative to true scores, and the direction and magnitude of observed context effects. The framework is illustrated empirically in a study of contrast effects involving performance judgments. Implications for reliability, validity, and agreement of behavior judgments in practice are explored.     

Controlling the Ground Reaction Force During Lifting

The control of the ground reaction force vector relative to the center of gravity (CoG) was examined while subjects performed a back-lifting task. Six male subjects (aged 24.0 +/- 2.5 years) repeatedly lifted a barbell. A biomechanical analysis that used a linked segment model revealed that the summed rotations of body segments during lifting yielded a specific rate of change of the angular momentum of the entire body. This equaled the external moment provided by Fsubg; relative to CoG. This implies that multisegment movements involve control of the angular momentum of the entire body through an appropriately directed Fsubg;. Thus, in dynamic tasks Fsubg; is pointed away from rather than lined up with the CoG, as is the case in static tasks.