Frequency discrimination near masked threshold

Frequency DLs (Δf) at 1000 Hz were obtained in quiet and under masking conditions similar to those used in pitch-shift experiments, narrow-band noise at levels of 60, 80, and 100 dB SPL and tones at 15 dB SL or less. The Δfs were obtained by means of a tracking task in which the S controlled the input voltage to a frequency modulator. Characteristic improvement was seen when Δf was plotted as a function of sensation level. However, noise level itself was a significant factor, with more intense noise resulting in larger Δfs for tones of equal sensation level re masked threshold. This departure from previous findings is attributed to the signal and noise levels used, although the possibility exists that it is due to the use of modulated tones.     

Monitoring simultaneous auditory messages

If a S is asked to monitor two simultaneous auditory speech messages and to report only on the occurrence of target words appearing at random in either message, then it is shown that he witt fail to detect all of them but will detect significantly more than half. The targets used in these experiments were immediate repeats of text words. The results reject theories that part of the sensory input is blocked or that all is recognized. Detection performance was a function of rate of speech and of intertarget interval; there was a small, not significant, effect of instruction to recognize message content.     

Similarity judgments of line length

Nine Ss judged similarity of pairs of lines on a scale from 0 to 100, and 14 Ss made magnitude estimations of similarity of pairs of lines. The two scales of similarity were linearly related. Scale values for subjective length were obtained in one dimension using a nonmetric multidimensional analysis. Subjective length was found to be logarithmically related to objective length, and similarity was found to be an exponential     

Recency discrimination predicted from absolute lag judgments

An experiment is described which tests the plausibility of the assumption that two-alternative forced-choice (2AFC) recency discrimination is based on an independent lag estimate of each item. 39 Ss made absolute recency judgments for items (common nouns) at varying lag intervals while an independent group of 74 Ss made 2AFC judgments for pairs of items at comparable lag combinations. It was found that the absolute judgment data generated accurate predictions of 2AFC performance.     

The relationship between cognitive,motor-kinesthetic,and oculomotor adaptation

The literature concerning adaptation to prism indicates that several adaptive mechanisms may be important. The particular mechanism or mechanisms involved depends (at least in part) upon the type of adaptive exposure. In the present study. three adaptive mechanisms (cognitive. oculomotor, and motor-kinesthetic) were investigated. Ss were asked to point in the dark at an illuminated target. The target was seen displaced from its veridical position due to a wedge prism placed before S’s right eye. The left eye was occluded. Ss then viewed their visual target pointing errors through the displacing prism without seeing any part of their bodies. One group of Ss was instructed to ignore these prism-induced errors and to continue pointing at the target’s visual position. A second group of Ss was instructed to compensate fully for their errors and to at tempt to eliminate them on all future trials. For the latter group errors were completely eliminated, while for Ss instructed to ignore their errors, relatively small improvement in visual target settings occurred. This improvement was called cognitive adaptation, since it depended on the S’s conscious control. In addition. for both conditions. evidence was found that allowing Ss to view their prism-induced pointing errors resulted in some form of motor-kinesthetic adaptation. This adaptation was hypothesized to represent a change in the judged position of the pointing hand relative to its felt position. It was concluded that this motor-kinesthetic adaptation was dependent, in part, upon cognitive information concerning the effects of the prism and that it serves to reduce conflict between cognitive and visual cues, i.e., between what S believes and what he sees.     

Individual half-judgment brightness functions

Nine Ss made half-judgments of each of nine brightness standards. Individual half-judgment brightness functions were constructed, one for each of the two threshold forms of the power law. The ω-Law (translation on the psychological axis) provided a better fit to the half-judgment data than did the ?-Law (translation on the intensity axis). A test of scale consistency for the fractionation method was confounded with the power law hypothesis, but the data are interpreted as providing fair support for the method independent of the form of the power law. The effect of Standard on exponent estimates was significant for both forms of the law, and the effect of Standard on threshold estimates was significant for the ?-Law but not for the ω-Law. Both forms of the law contain a so-called threshold parameter, but the interpretation of this parameter as a threshold was rejected for the ?-Law and accepted for the ω-Law.     

Variables underlying the recognition of random shapes

Speed of sorting decks of 32 cards with two alternative stimuli was measured. The stimuli were pairs of dots with attributes of distance between dots, angle of orientation of the pair, and position of the pair to the right or left of center. The attributes varied in relative discriminability and were used in all possible pair- and triple-correlated (redundant) combinations. Results showed an increase in speed of sorting with either an increase in discriminability or an increase in number of redundant attributes. It is argued that the increased speed with addition of redundant attributes is due both to a selective serial processing of attributes (requiring attribute separability) and to an increased discriminability with combined attributes (requiring attribute integrality).     

Verbal interference in a perceptual comparison task

When Ss had to indicate if the colors of pairs of items from the Stroop test were the same or different, the usual interference effect was completely eliminated. However, when the verbal information consisted of SAME and DIFF rather than color names, interference was reestablished. This indicates that the perceptual comparison task does not eliminate interference simply by rendering Ss insensitive to the meanings of words.