Modification of muscle activation patterns during fast goal-directed arm movements

The motor programming of fast goal-directed arm movements was studied in a tracking task. A target jumped once or twice randomly to the left or right direction with an interstimulus interval (ISI) in a range between 50 and 125 msec. Double step stimuli were either two steps in the same direction (C-trial) or in opposite direction (R-trial). Tracking results show that at the beginning average EMG-activity is the same for responses to single step trials, R-trials and C-trials. Differences set in after some time equal to or somewhat shorter than ISI. It was concluded that muscle activation patterns of fast goal-directed movements are not preprogrammed but that they can be modified during the movement. The time interval between second target step and the moment when EMG activity of the double step response deviates from the EMG activity of a single step (RT2) could be smaller than the time interval between first target displacement and EMG onset. (RT1). If modification of the muscle activation pattern required a longer or larger activation of the active muscle, RT2 tended to be smaller than RT1, whereas RT2 was about equal to RT1 if the new muscle activation required a termination of the ongoing muscle activation pattern and the activation of another muscle.     

Replicability and invariance of dimensions of parental rearing behaviour: Further Dutch experiences with the EMBU

In a recent article, Ross, Clayer and Campbell (1983) argued and showed by means of factor analysis that the number of child-rearing dimensions found previously with the EMBU appears to be dependent on the type of rotation used in factoring. Based on the assumption and empirical evidence that the dimensions found earlier are significantly correlated, Ross et al. (1983) argued that Oblique rotation would appear to give rise to a larger number of distinguishable dimensions than previous analyses (e.g. Arrindell, Emmelkamp, Brilman and Monsma, 1983). We contend that their conclusion was based on an inappropriate analysis of the data with a neglect of relevant psychometric principles. Employing objective techniques of factorial invariance the factors obtained in our previous study were shown here to be congruent across rotational procedures (Oblique vs Varimax). Supporting the stability and factorial and construct validity of the EMBU Rejection, Emotional Warmth, Overprotection and Favouring Subject dimensions, they were shown in further analyses to be: (a) replicable across split samples of phobics (Ns: 421 vs 420); and (b) invariant across distinct populations (phobics, N = 841 vs normals, N = 277).     

Actors' and Observers' attributions,self-serving bias and positivity bias

An experiment was conducted to investigate the influence of evaluative factors upon preference for situational and dispositional attributions. Subjects listened to a tape recording of a group discussion on smoking, two actors presenting arguments in favour of smoking and two actors arguing against smoking. Subjects were then asked to explain in attributional terms the actors' behaviour and their own smoking behaviour, their evaluation of smoking being separately assessed. Results provided no support for a general self-other attributional difference; subjects did not explain their own behaviour in more situational terms while explaining the behaviour of others in more dispositional terms. Findings indicated that individuals generally attributed positively evaluated behaviour to dispositional factors and negatively evaluated behaviour to situational factors, regardless of attributor role (actor or observer). The results are interpreted as offering support for a positivity bias in attributional preference.     

Some evidence for a limited capacity parallel selfterminating process in simple visual search tasks.

An experiment was carried out in order to investigate the questions of exhaustive vs selfterminating and serial vs parallel processing in a simple visual search task. In the experiment, 1, 2 or 3 letters were placed on an imaginary circle round the fixation point. Two different letters were used, one of which was defined as the ‘signal’. Ss had to respond ‘yes’ when one or more signals were in the display, ‘no’ otherwise. The number of signals in the display was varied from ‘no signals’ to ‘all signals’.A decrease in latencies with increasing number of signals for a fixed number of elements presented was observed indicating a selfterminating search. A decrease in latencies with increasing number of elements when only signals were presented was taken as evidence for a parallel selfterminating process. A further analysis of the error data showed that a limited capacity system had to be assumed. It was shown that it was possible to construct the overall pattern of latencies over conditions from the error data obtained.     

A search for predictive factors in institute supervised cases: a retrospective study of 183 cases from 1959-1966 at the Boston Psychoanalytic Society and Institute.

The purpose of this project was to determine if it is possible to predict from the information contained in the write-ups of the preliminary evaluations of patients accepted for Institute supervised analyses those patients who would successfully complete their analyses and those who would not. Three raters independently studied the write-ups of 183 cases treated at the Boston Institute during the period 1959-1966. Each rater filled out a questionnaire of 105 items which were thought to be of possible predictive value. Outcomes were sought from the analysts who treated the patients. 130 outcomes were obtained and revealed that the patients fell into 4 distinctly different outcome groups: (Group 1) those who completed analysis by mutual agreement between the analyst and patient; (Group 2) those who prematurely terminated their analyses against the advice of their analysts; (Group 3) those whose analyses were prematurely interrupted by their analysts; (Group 4) those whose analyses became interminable. Statistical analyses were done to see which of the 105 predictor items distinguished these four distinct outcome groups. Many of the predictor items were not useful because they either showed no variation among patients, or were too often left blank, or were rated with very low interrater agreement. Of the remaining items, we found ten items which did show a highly significant difference between Group 1 patients and those patients in at least one of the other three outcome groups. We found five other predictor items which showed large, although not quite statistically significant, differences between Group 1 and at least one of the other three groups. Of these 15 items, 7 dealt with family history. The others concerned the patient's past history (2), object relationships (2), patient's sex (1), symptomatic state (1), field of endeavour (1), and history of previous psychotherapy (1). We found it made no difference in terms of these 4 outcome groups what the patient's diagnosis was or whether he was a 1st, 2nd, 3rd or 4th supervised case. Among the other negative findings were patient's age and the ability to experience and tolerate felt anxiety. These did not distinguish any of the outcome groups. These findings show that additional predictively useful information is present in the preliminary evaluations of patients already screened and accepted for Institute analysis by trained evaluators. These results suggest that one particularly important area on which to focus future attention is family history.     

Direct visual access in reading for meaning

Two experiments examined whether phonological receding is an obligatory stage in reading for meaning or whether direct access to a word's semantic representation is the general rule. The first study demonstrated that the time to make a semantic decision about a pair of words was much more delayed by misspelling than was the time to make a phonological one. The second study investigated the effect of varying the syllabic length of a word on reaction time in a category decision task. While reaction time varied with the semantic difficulty of the category decision, it generally proved invariant with respect to syllabic length. It is argued that reading for meaning generally uses a direct route from visual form to semantic representation.     

Testing some implications of the sensory physiological model of the time sense

Summary In this paper some implications of the pulse generator model of time perception have been tested. In the case of serial (re)production of an interval a lengthening effect occurs. Generally, this phenomenon is explained by assuming that the time-keeper is driven by the state of general physiological activation which decreases in the course of the task. An experiment was carried out in which EEG activity was recorded during the time estimation process. It appeared that a lengthening effect occurred, but there was no correlation between the reproduction times and the means of the EEG spectra, however. In a second experiment two series of time estimations were compared as a function of administering a placebo and methamphetamine. In the latter case the model predicts that no lengthening will occur since arousal (at least for a short period of time) is kept at a high and constant level. In fact, no differences between the regressions of the time estimation curves before and after drug administration have been found, so that the predictions of the model as regards the origin of lengthening could not be supported. It is suggested that the nature of the effect should be studied within the framework of the cognitive theory of time experience which offers various starting points in this respect.     

Earman on the causal theory of time

Conclusion I have so far ignored Earman's Section IV in which spatiotemporal coincidence is discussed. The answer will be clear from the preceding: the exact definitions and principles of the exact theories we have displayed are to be discussed with reference to the special and not the general theory of relativity. But moreover, Earman's transition from (C) to (1) assumes what we do not grant: that events are causally connectible exactly if the points in the mathematical space-time at which they are located are linked by a causal curve.This captures in a nutshell my own conclusions. The first is that the causal theory, after its success vis-à-vis the STR, must now provide a detailed analysis of spatiotemporal concepts in the GTR. The second is that the points raised by Earman do not provide substantive reasons for doubting the adequacy of the causal theory to this task, because Earman insists in his extrapolations on a much closer relation between the empirical structure of events and the mathematical structures that model it than ought to be assumed.I wish to acknowledge gratefully my debt to Dr. A. Grünbaum, University of Pittsburgh, to Dr. C. Glymour, Princeton University, and to the support of the John Simon Guggenheim Memorial Foundation.     

Sequence influence on the organization of meaningless serial stimuli: economy after all

This article provides evidence for an extension of structural information theory, a theory which describes perceptual organization formally, into a more general theory of representation that takes the role of organizations obtained earlier into account. In eight experiments, subjects study series of colored dots. Each series contained 6-8 dots of different colors, and viewing time was between 400 ms and 60 s. In several experimental procedures, subjects recalled the series presented. The experiments systematically varied the economy of the organizations of the series as described by structural information theory as well as a number of aspects of the context in which the series were presented, like order of presentation of a series, order between the series, viewing span, viewing time, and recall procedure. Recall was influenced both by the economy as well as by the context. It is shown how the context influences the relative strength of the most economical organization as compared with rival, local organizations. A structured network model is presented that accounts for the influence of both the economy and the context.