Motor limitation in dual-task processing under ballistic movement conditions

The standard bottleneck model of the psychological refractory period (PRP) assumes that the selection of the second response is postponed until the first response has been selected. Accordingly, dual-task interference is attributed to a single central-processing bottleneck involving decision and response selection, but not the execution of the response itself. In order to critically examine the assumption that response execution is not part of this bottleneck, we systematically manipulated the temporal demand for executing the first response in a classical PRP paradigm. Contrary to the assumption of the standard bottleneck model, this manipulation affected the reaction time for Task 2. Specifically, reaction time for Task 2 increased with execution time for Task 1. This carryover effect from Task 1 to Task 2 provides evidence for the notion that response execution can be part of the processing bottleneck.     

Programming of time-to-peak force for brief isometric force pulses: effects on reaction time

According to the parallel force unit model (PFUM) the programming of an isometric force pulse requires the specification of the number of force units and force unit duration. The programming of a force pulse with minimal time-to-peak force is an exception, however, as force unit duration is limited by the minimal possible value, which should be easier to adjust than larger force unit durations. Therefore, the duration of the programming process should be shorter for these force pulses and hence should result in shorter reaction time (RT). Four experiments assessed this prediction using a response precueing procedure. In each experiment the participants produced isometric flexions with their left or right index finger, and time-to-peak force was manipulated within a block. The results are consistent with the predictions of PFUM. The results, however, are at variance with alternative accounts which assume that RT depends primarily on response duration or rate of force production.     

Online response preparation in a rapid serial visual search task

Online response preparation was assessed in a visual search task using rapid serial visual presentation. In each trial, a series of letters was presented sequentially, and participants were instructed to make a target-present response if a prespecified target letter was presented or a target-absent response if it was not. Measurements of response preparation using both probe reaction time and the lateralized readiness potential indicated that preparation of the target-absent response increased near the end of the sequence. Most of the increase appeared to be due to direct priming of the target-absent response by nontarget letters, but part was due to the increased conditional probability of this response near the end of the sequence. These results extend previous studies of response preparation by showing online response preparation during a temporally extended reaction time task.     

Incarcerated adolescent girls: personality, social competence, and delinquency

The aim of this study was to gain greater insight into the relationship of delinquency to personality and social competence in incarcerated girls. It was hypothesized that agreeableness and conscientiousness would correlate negatively with delinquency, and that the sensation-seeking aspect of extroversion would correlate positively. Two theoretical views were used to predict the relationship between social competence and delinquency: (a) delinquency as an expression of lack of social competence (i.e., social deficit), and (b) delinquency as socially competent and rationally analyzed behavior. The first view implies a negative correlation between delinquency and social competence, while the second indicates a positive one. The participants were thirty-three 12- to 18-year-old incarcerated girls. An adaptation of the Self-Reported Delinquency Scale was used for measuring delinquency; personality was measured using the Five-Factor Personality Inventory; and the Scale for Interpersonal Behavior was used to measure social competence. Agreeableness was not found to correlate with the overall delinquency score or with any specific type of delinquency or crime. The more crimes the girls reported, the less conscientious they were, and the more neurotic and open they were. The correlation between delinquency and extroversion was not statistically significant. A higher level of delinquency was accompanied by higher social competence when negative self-assertion was required (i.e., a low level of tension was felt in expressing negative feelings that were appropriate to the situation). In other social situations, however, the girls reported more situation-inappropriate feelings of tension. It was concluded that some personality factors and aspects of social competence can predict delinquency.     

Relation between EMG activation patterns and kinematic properties of aimed arm movements

Aimed flexion movements of the arm of different amplitude and duration were studied. Velocity and acceleration traces of movements with equal duration but different amplitude were equal, apart from a scaling factor (ratio between movement amplitudes). After appropriate scaling, EMG activity of the first agonist burst for these movements superimposed. This was not true for EMG activity in the antagonist muscle. For movements with equal amplitude, but different duration, the time to peak acceleration was constant for all MT'. Except for this fact, traces of acceleration, velocity, and agonist activity following the time of peak acceleration were about equal after appropriate scaling in time and amplitude. The integral of EMG activity in the first agonist burst increased linearly with peak velocity. For the antagonist burst, the integrated EMG activity increased more than proportionally. During movements made as fast as possible, subjects used a different strategy by varying the duration of the accelerating phase for movements of different amplitude. Movement amplitude was achieved by adjusting the duration of the agonist burst and the onset time for the antagonist muscle. Amplitude of the antagonist burst was constant within a narrow range for movements of different amplitude. These results did not change when the inertial mass was doubled by loading the arm with an additional mass.     

Knowledge management in strategic planning: The case of the dutch fourth report

This article examines the management and use of knowledge in a relatively complex planning and policy process, i.e., the preparation and implementation of the Fourth Report on Physical Planning in the Netherlands. Attention is given to the organization of this process; the manner in which research, policy design and plan negotiation were intertwined in the various phases of the process; and the solutions developed for the problem of obtaining sufficient knowledge without losing the impetus essential to policy-making. General conclusions are derived especially concerning the interrelationship between policy-making and the accretion and depletion of knowledge stocks. While his earlier publications were primarily concerned with the application of demographic research in spatial policy, he has more recently shifted his attention to knowledge utilization problems in general.     

Hypothesis sampling systems among preoperational and concrete operational kindergarten children

Groups of 60 preoperational and 60 concrete operational kindergarten children received stimulus differentiation training either with feedback (experimental groups) or without (control groups), prior to a series of discrimination-learning problems in which a blank-trial probe, used to detect the child's hypothesis, followed each feedback trial. The concrete operational children manifested significantly better performances than the preoperational on seven of eight dependent measures examined. There were also significant differences in favor of the experimental groups on three dependent measures. While the results were generally consistent with predictions derived from Piagetian stage theory, it was suggested that this theory must be elaborated to include a perspective derived from conventional developmental learning theory in order to adequately account for these and other data.     

Use of Reinforcement Technique with a First Grade Boy

A reinforcement technique in counseling was used to modify a first grader's attending behavior. Pre- and post-counseling measurements were made and cumulative records were kept of attending time in counseling sessions and in arithmetic lessons, and a record was kept of completion vs. noncompletion of arithmetic assignments. The assessments made in regard to the arithmetic lessons enabled an investigation of transfer effects from counseling to the academic area. An investigation of transfer effects was also informally made relative to other school situations. Results showed increased attending behavior in counseling and in the classroom, and a marked improvement in completion of assignments, and were interpreted as supporting the use of a behavioral approach in elementary school counseling.     

The development of preferences for own-race versus other-race faces in 3-, 6- and 9-month-old Caucasian infants

Visual preferences for pairs of African and Caucasian faces were repeatedly assessed in 3-, 6- and 9-month-old Caucasian infants with a preferential looking paradigm. Two different patterns of preference development were found: First, the spontaneous own-race preference at three months reported in the literature tilts to a preference for other-race faces at nine months passing through a null-preference at six months. This replicates the pattern recently reported for Asian infants [Liu et al. (2015). Development of visual preference for own- versus other-race faces in infancy. Developmental Psychology. doi:10.1037/a0038835]. Second, at all three ages fixation time towards Caucasian faces significantly reduces across the consecutive trial presentation. This is a similar effect as in novelty preference studies to occur after a sufficiently long familiarization phase. Both patterns can be explained in terms of an advantaged own-race face processing with the emerging Other-Race-Effect.