The perceptual properties of electrocutaneous stimulation: Sensory quality,subjective intensity,and intensity-duration relation

A preliminary and two main experiments designed to examine the perceptual properties of electrocutaneous stimulation are reported. The stimuli used were single short pulses varying in intensity and duration. In Experiment 1, the exponents of power functions fitted to electrocutaneous magnitude estimation data were determined together with the sensory qualities induced by electrical stimulation. The results showed that there was no correlation between the exponent values and the sensory qualities. The mean exponent was 1.2. In Experiment 2, an intensity-duration trading function was constructed from the data obtained from identifying the induced sensory qualities. The results showed that the critical duration increases from 30 to 300 msec with increasing sensation level. These findings are compared with the properties of other sense modalities.     

The role of motion direction selective extrastriate regions in reading: a transcranial magnetic stimulation study

Why reading ability is correlated with motion processing ability is perplexing. Activity in motion direction processing regions (Area V5/MT+) was perturbed by means of repetitive transcranial magnetic stimulation (rTMS) to examine its effect on reading. A functional probe (significant shortening of the motion aftereffect) was used to identify Area V5/MT+. Right-handed participants (8 m, 8 f) received three 7.5 min blocks of rTMS, after which two phonological and one orthographic reading tasks were administered. Application of rTMS to Area V5/MT+ (as compared to a non-rTMS baseline) significantly decreased performance only during non-word naming. The pattern of naming errors and the absence of deficits on the second phonological task were not consistent with a role for Area V5/MT+ in phonological decoding. Instead, its role in reading may be limited to image stabilization and/or letter localization.     

The hierarchical order of processes underlying the direction illusion and the direction aftereffect

Motion perception involves the processing of velocity signals through several hierarchical stages of the visual cortex. To better understand this process, a number of studies have sought to localise the neural substrates of two misperceptions of motion direction, the direction illusion (DI) and the direction aftereffect (DAE). These studies have produced contradictory evidence as to the hierarchical order of the processing stages from which the respective phenomena arise. We have used a simple stimulus configuration to further investigate the sequential order of processes giving rise to the DI and DAE. To this end, we measured the two phenomena invoked in combination, and also manually parsed this combined effect into its two constituents by measuring the two phenomena individually in both possible sequential orders. Comparing the predictions made from each order to the outcome from the combined effect allowed us to test the tenability of two models: the DAE-first model and the DI-first model. Our results indicate that DAE-invoking activity does not occur earlier in the motion processing hierarchy than DI-invoking activity. Although the DI-first model is not inconsistent with our data, the possible involvement of non-sequential processing may be better able to reconcile these results with those of previous studies.     

The extraretinal signal for the visual perception of direction

The dependence of the perception of direction on two kinds of extraretinal signals was measured by asking Ss to indicate the position of a fixation target relative to the subjective straight ahead. Outflow was studied by making such localizations while the fixating eye was loaded by means of weights attached to a suction contact lens. Inflow was studied by making such localizations with brief test flashes to a passively rotated eye while the other eye fixated. Shifts in the perceived direction, of the fixation target were in line with predictions from outflow theory and not influenced by conflicting inflow signals.     

Localization of electrocutaneous stimuli on the fingers and forearm: Effects of electrode configuration and body axis

Four experiments were done on the effects of electrode configuration (concentric vs. unifocal) and body axis (longitudinal vs. transverse) on localization of electrocutaneous pulse stimuli at the fingers and forearm. Subjects pointed to the apparent location of current pulses. For the transverse placement of electrodes, pulses were localized correctly, whatever the configuration and the body site might be. In addition, intrasubject variability at the forearm was smaller for the transverse axis than for the longitudinal axis. For the longitudinal placement of electrodes, pulses were localized as a function of configuration and body site. At the fingers, concentric electrodes provided precise localization but unifocal electrodes provided a great mislocalization; and intrasubject variability of localization was larger for the unifocal electrodes than for the concentric electrodes. At the forearm, whatever the configuration might be, the pulses were localized more proximally than the stimulus site; and intrasubject variability of localization did not differ between the configurations. These results are related to Boring’s anchor theory, apparent distance between two points, and the localization of other somatosensory stimuli.     

The direction of movement of machine controls

Experiments are described in which the relation between the direction of movement of a control and display was varied in order to determine what relationships are likely to cause least confusion to the operator of a machine. Two different types of task were used: a task consisting of intermittent stimuli whose rate of presentation could be varied, and a continuous pursuit task.

It is found that accuracy of performance varies with the degree of remoteiiess of the directional relationship from those met in everyday life, with the complexity of the task, with the ability of the subject, and there is some indication that under certain Conditions it may vary with the breadth of his attention. Awareness of the response aspect of the situation in these simple sensori-motor tasks, it is suggested, although necessary in the early stages of learning, may be associated in the later stages with confusion and error.     

The practice of psychotherapy and spiritual direction

The author compares and contrasts insight-oriented psychotherapy, supportive psychotherapy, and spiritual direction in relation to goals and methods; management of resistance, transference, and countertransference; and selection criteria. The enhancement of spiritual formation through insight-oriented psychotherapy and supportive psychotherapy is also discussed.     

The direction of bilateral transfer depends on the performance parameter

To acquire a more comprehensive understanding of the learning benefits associated with bilateral transfer and to gain knowledge of possible mechanisms behind bilateral transfer, we investigated the transfer direction of several parameters which are assumed to represent important features of movement control in a visuo-motor task. During the study, participants learned a multidirectional point-to-point drawing task in which the visual feedback was rotated 45° and the gain was increased. Performance changes of the untrained hand in movement time, trajectory length, normalized jerk, initial direction error, ratio of the primary sub-movement time to the total movement time, and the accuracy of the aiming movement after the primary sub-movement were investigated as indices of learning from bilateral transfer. The results showed that performance parameters related to the initial production of the movement, such as the initial direction, ratio of primary sub-movement to the total movement time, and movement accuracy after the primary sub-movement, only transferred to the non-dominant, while hand performance variables related to the overall outcome, such as movement duration, movement smoothness, and trajectory length, transferred in both directions. The findings of the current study support the basic principle of the “dynamic dominance model” because it is suggested that overall improvements in the non-dominant system are controlled by trajectory parameters in visuo-motor tasks, which resulted in transference of the afore mentioned production parameters to rather occur to the non-dominant hand as opposed to transference to the dominant hand.     

The typical rank of tall three-way arrays

The rank of a three-way array refers to the smallest number of rank-one arrays (outer products of three vectors) that generate the array as their sum. It is also the number of components required for a full decomposition of a three-way array by CANDECOMP/PARAFAC. The typical rank of a three-way array refers to the rank a three-way array has almost surely. The present paper deals with typical rank, and generalizes existing results on the typical rank ofI × J × K arrays withK = 2 to a particular class of arrays withK ≥ 2. It is shown that the typical rank isI when the array is tall in the sense thatJK − J < I < JK. In addition, typical rank results are given for the case whereI equalsJK − J. The author is obliged to Henk Kiers, Tom Snijders, and Philip Thijsse for helpful comments.     

The functional arrangement of objects biases gaze direction

Psychonomic Bulletin & Review - A growing number of studies suggest that semantic knowledge can influence the control of gaze in scenes. For example, observers are more likely to look toward...     

Effects of pointing direction and direction predictability on event-related lateralizations of the EEG

In two experiments, we investigated hemispheric electroencephalography (EEG) differences in 9(12) healthy volunteers during pointing to lateral and central targets. The questions addressed were whether horizontal pointing direction and the predictability of pointing direction modulated hemispheric differences (event-related lateralizations of the EEG = ERLs). To vary pointing direction predictability, targets were displayed either randomly at one of nine different positions on a screen (random) or at the same horizontal position in five subsequent trials (sequenced) while vertical positions varied randomly. Event-related lateralizations (ERLs) varied with pointing direction. This was true across changes in target eccentricity and pointing distance. Foci of the ERLs were in premotor and posterior parietal cortex, which might reflect the critical involvement of these areas in the control of visually guided reaching. Direction predictability reduced the parietal and premotor ERL before pointing onset, probably reflecting a lesser effort in visuomotor transformation. Predictability also added an overlying N2pc component to the early ERL after target onset and increased direction effects during movement.     

Problem representation: The effects of spatial arrays

Two studies examined how characteristics of spatial arrays contribute to efficient problem representation. Thirty-two adults were presented with information about family relationships in one of two arrays: a hierarchy or a matrix. Their answers to two different sets of questions were timed. The matrix format was superior to the hierarchy for one set of questions only; no differences between the arrays emerged for the other set. The data were interpreted in terms of how the family relationships were mapped onto the arrays; the mapping differences between the arrays affected the number of mental steps needed to solve some questions, but not others. In a second experiment (N=32), the same problem information was remapped onto the arrays, with the mapping relations reversed. As predicted, the pattern of response times exactly reflected the change in mapping. It is proposed that, for spatial arrays, efficiency of problem representation is best understood in terms of the number of mental steps in the problem solution.     

Reaction time to the onset and offset of electrocutaneous stimuli as a function of rise and decay time

Reaction times were obtained to the onset and offset of 70-cps electrocutaneous signals of five rise and decay times and five intensity levels. The results show that both onset and offset RTs increase linearly with increased rise and decay times. With fast rates of rise or decay, the onset produces faster RTs than the cessation of stimulation. The opposite effect is found when long rise and decay times are used. Interpretations of these results are given in terms of neural adaptation and accommodation.     

Reaction time to the onset and offset of electrocutaneous stimuli as a function of rise and decay time

Reaction times were obtained to the onset and offset of 70-cps electrocutaneous signals of five rise and decay times and five intensity levels. The results show that both onset and offset RTs increase linearly with increased rise and decay times. With fast rates of rise or decay, the onset produces faster RTs than the cessation of stimulation. The opposite effect is found when long rise and decay times are used. Interpretations of these results are given in terms of neural adaptation and accommodation.     

Adaptation in the constancy of visual direction tested by measuring the constancy of auditory direction

Modification of the constancy of visual direction was produced by partially adapting Ss to the displacements of the visual field caused by magnifying lenses during 1 h of continuous head turning. The adaptation effects were measured by determining the range of perceived target immobility before and after this adaptation period. A method for measuring the range of apparent immobility of an auditory signal during head movements was developed and employed to test whether a modification of the constancy of visual direction transfers to the constancy of auditory direction. No such transfer was found, and it was concluded that a modification of the constancy of visual direction does not consist in an altered evaluation of kinesthetic cues for head turning. The method and the equipment used in the investigation of the constancy of visual direction are described; knowledge of the previous brief publications on this topic is not needed.