EMG waveform duration: A validation method for the surface electromyogram

The electromyogram (EMG) recorded with surface electrodes was examined using a triggered oscilloscope technique. When all but the high-amplitude waveforms in a given segment of activity were excluded from analysis, it was found that the duration of the remaining waveforms was specific to the muscle that produced them. That is, waveforms of a given duration were recorded whenever conventional indices-observable contraction, joint movement. needle recordings-showed activity in a specific muscle. This led to the suggestion that waveform duration might be used to validate the surface EMG. The suggestion. which is limited by the need to control posture and electrode placement, both of which may influence waveform duration, was illustrated in application to psychological research.     

Parent and child perceptions of Boszormenyi-Nagy's ethical dimensions of the parent-child relationship

The parent-child relationship plays an important role in Boszormenyi-Nagy's contextual therapy. This article presents the results of four interview studies of the opinions of parents and children about their ethical relationship.The children in these studies were five-to-seven-year-olds, 10-to-12 year olds and 15-year-olds. In one study only the mothers were interviewed, in the other three both parents participated. In all 73 children, 62 mothers, and 43 fathers were interviewed. The majority of parents and children agreed with most aspects of Nagy's theory about the parent-child relation, but there were some notable exceptions. Very few shared Nagy's ideas about entitlement. The age of the child had a clear effect on the opinions of the children on the dimensions of trust/reliability, loyalty and shifting of the balance with age of the child and on the opinions of the parents on the dimensions of childrens' rights, parents' rights, and balance of fairness. The sex of the interviewee had some effect: Mothers and fathers differ on the dimension of parents' rights and adolescent girls and boys differ on the dimensions of childrens' rights and parents' duties.     

The role of position in object selection in vision

Summary Within contemporary visual-information-processing psychology, two classes of selective-attention theories can be distinguished: position-not-special theories and position-special theories. The position-not-special theories postulate that attentional selection by colour, by form, and by position are equivalent selective operations. The position-special theories assume that selection by position is more basic or direct than selection by colour or by form. Examples of both types of theory are briefly described, and irrelevant and relevant evidence is critically discussed. It is concluded that the relevant evidence is directly compatible with the position-special views and that the position-not-special theories require additional extraneous assumptions. The position-special model presented in Van der Heijden (1992) is elaborated in further detail. It is shown that this model is compatible with two important and often substantiated assumptions of the position-not-special theories: the assumption that pre-attentive analysers organize the visual scene in objects against a background, and the assumption that visual-selective attention can be directed at objects isolated in this way. This position-special theory is a parsimonious theory because it can identify the mentalistic conceptselective attention with the materialistic conceptspatial position.     

Auditory accessory effects on visual processing

A series of experiments on intersensory facilitation demonstrates that non-informative sound of low to moderate intensity (30/80 dB) facilitates the reaction to a visual stimulus. By manipulating the preprocessing and perceptual stages of the visual signals, it appears that auditory intensity reduces choice reaction time independently from the positive influence of the intensity and duration of the visual imperative signal, but interacts with the effect of stimulus degradation. Degraded stimuli take more profit of the sound than intact stimuli. Besides a short-term activation effect, originated by accessories of the auditory modality, on the motor adjustment stage (cf. Sanders 1983), the results suggest that the accessory influences the stage of feature extraction.     

Is the match/mismatch model based on a statistical artefact?

In the match/mismatch model, recently formulated by Rachman and coworkers, it is stated that incorrectly predicted aversive experiences are generally followed by an immediate adjustment of the predictions concerning aversiveness of the next experience. This model can be considered to reflect a psychological process of the formation of expectations. In the present article it is argued that a simple H0 model, assuming that predictions are completely randomly generated by the subject, may account for the same effects. This H0 model is used in a stringent test of empirical data to determine if there are any effects of the discrepancy between prediction and experience on next prediction that exceed the effects explained by the H0 model. Although the H0 model produces effects very similar to the empirically observed effects, there is clear support for the hypothesized influence of the discrepancy between prediction and experience. Therefore, the model appears to reflect 'real' psychological processes and not chance findings.