Is the discrimination of motion-path length unique?

Discrimination of the extent of a motion path may present a special problem since the discrimination calls on memory for changing position and involves pursuit movements of the eye. To determine how these factors affect judgment, discrimination of extents represented by motion paths, successively appearing endpoints, and simultaneously present endpoints was compared under a variety of eye-movement conditions: fixation, pursuit, and saccadic. Discrimination was assessed by the method of adjustment and also by the method of magnitude estimation. Discrimination of motion path extent was found to be as accurate as discrimination of an interspace demarcated by simultaneously presented points or by successively presented points. This was true for brief single presentations of the extents as well as for repeated exposures to the extents. The findings were applied to the analysis of the perception of velocity and the perception of extent.     

Operant conditioning of the EEG in two patients with epilepsy: Methodologic and clinical considerations

Methodologic and clinical considerations are discussed in sensorimotor rhythm (SMR) biofeedback research on two dissimilar but severe epileptic males. The first case, an akinetic epileptic who prior to feedback training experienced 80–100 clinical seizures every 10 hours, showed considerable seizure reduction after 6 months of SMR and epileptiform training. A number of methodologic and instrumentation advances were pioneered with the akinetic patient: (1) development of and ultra-sharp band-pass filter; (2) use of epileptiform inhibit and feed-back circuitry; (3) use of monetary rewards as additional incentive; (4) use of correlational analysis for evaluation of acquisition in the major dependent variables and; (5) use of noncontingent feedback and rein-forcement as control techniques. The second case, a psychomotor epileptic, also showed therapeutic benefit from SMR training. Clinical information regarding the effect of anticonvulsant medications on the course and therapeutic outcome of SMR training are described. In conjunction with operant conditioning of 12 Hz activity, corresponding changes for other EEG parameters are examined.     

Discrimination of time intervals marked by brief acoustic pulses of various intensities and spectra

Experienced observers were asked to identify, in a four-level 2AFC situation, the longer of two unfilled time intervals, each of which was marked by a pair of 20-msec acoustic pulses. When all the markers were identical, high-level (186-dB SPL) bursts of coherently gated sinusoids or bursts of band-limited Gaussian noise, a change in the spectrum of the markers generally did not affect performance. On the other hand, for 1-kHz tone-burst markers, intensity decreases below 25 dB SL were accompanied by sizable deterioration of the discrimination performance, especially at short (25-msec) base intervals. Similarly large changes in performance were observed also when the two tonal markers of each interval were made very dissimilar from each other, either in frequency (frequency difference larger than 1 octave) or in intensity (level of the first marker at least 45 dB below the level of the second marker). Time-difference thresholds in these two latter cases were found to be nonmonotonically related to the base interval, the minima occurring between 40- and 80-msec onset separations.     

Historical comparisons: Testing psychological hypotheses with cross-era data (1)

Cross-era research, an approach which involves developing and testing social science hypotheses in terms of historical time-series data, is first discussed as regards its relationship to other comparative research approaches. Some examples of cross-era research in psychology are described. Special problems that arise in cross-era research, and proposed methods of coping with them, are discussed as regards each of the three successive phases of research: creative hypothesis formation problems; difficulties that arise in the hypothesis-testing phase; and problems that emerge during the phase of communicating and utilizing the findings.     

Manipulation of response-contingent unconditioned-stimulus intensity in human eyelid conditioning: A two-phase model analysis

Four groups of human subjects were given 360 classical eyeblink conditioning trials. All groups received the same UCS (unconditioned stimulus) intensity on[Formula: see text] (nonconditioned response) trials but differed in the intensity presented on CR trials. Response probability increased as a positive function of UCS intensity on CR trials. Phase 1 of the two-phase model was longer when no UCS was presented on CR trials, but did not differ in duration among the remaining three groups. Most subjects could be described with a single operator in Phase 2, the operator limit increasing as a positive function of CR-contingent UCS intensity. For subjects requiring different operator limits on CR and[Formula: see text] trials, the latter was lower with high CR-trial intensities but higher with low CR-trialintensities. The results were interpreted to be more consistent with drive theory than with "law-of-effect" or two-factor theories.