The effects of auditory streaming on duplex perception

When a formant transition and the remainder of a syllable are presented to subjects' opposite ears, most subjects perceive two simultaneous sounds: a syllable and a nonspeech chirp. It has been demonstrated that, when the remainder of the syllable (base) is kept unchanged, the identity of the perceived syllable will depend on the kind of transition presented at the opposite ear. This phenomenon, called duplex perception, has been interpreted as the result of the independent operation of two perceptual systems or modes, the phonetic and the auditory mode. In the present experiments, listeners were required to identify and discriminate such duplex syllables. In some conditions, the isolated transition was embedded in a temporal sequence of capturing transitions sent to the same ear. This streaming procedure significantly weakened the contribution of the transition to the perceived phonetic identity of the syllable. It is likely that the sequential integration of the isolated transition into a sequence of capturing transitions affected its fusion with the contralateral base. This finding contrasts with the idea that the auditory and phonetic processes are operating independently of each other. The capturing effect seems to be more consistent with the hypothesis that duplex perception occurs in the presence of conflicting cues for the segregation and the integration of the isolated transition with the base.     

Effects of peripheral circular contours on dynamic spatial orientation

The rod-and-frame effect (RFE) was investigated with the use of a frame that oscillated about an axis at its center at five different frequencies, ranging from .013 to .213 Hz. The resultant RFE shifted continuously with the roll motion of the frame, and it was significantly larger at the lowest frequency (.013 Hz) than under comparable static conditions. The dynamic RFE was lowest at the higher oscillation frequencies. Oscillatory roll vection--apparent self-motion--was reported by 3 of the 9 subjects when the frame was oscillating at its highest frequency (.213 Hz). The subjects yielded large increases in the RFE during the sessions with reports of vection. Surrounding the kinetic frame with a circular contour eliminated all reports of vection and significantly interacted with frequency to reduce the RFE--but only at low frequencies. The reduction amounted to 21.2% averaged over all 9 subjects at the three lowest frequencies. A surrounding contour, therefore, suppressed low-frequency kinetic visual orientation information that might otherwise have produced larger changes in apparent self-orientation and perceived vertical. Vection-sensitive subjects differed from nonvection subjects by exhibiting (1) a high-frequency fall-off in real-motion gain, (2) a high-frequency enhancement in illusory-motion gain, and (3) only a small and nonsignificant increase in illusory-movement phase lag with increases in frequency.     

Rate of processing and judgment of response speed: comparing the effects of alcohol and practice

Both alcohol and practice affect choice reaction time. The present study was conducted to investigate the possibility that impairment from alcohol and improvement with practice could be attributed to changes in the efficiency of control mechanisms (Rabbitt, 1979a), some of which depend upon the ability to judge response speed accurately. Twenty subjects participated in a four-choice reaction time experiment in which they received no alcohol (NA) in Session 1 and either no alcohol (10 subjects) or 0.8 ml alcohol (A) per kilogram of body weight (10 subjects) in Session 2. The task was to respond as fast and as accurately as possible to each stimulus. In addition, subjects were required to press a fifth key after any response that they considered to be both fast and accurate. Subjects had no difficulty in performing this task: (1) there was a significant difference of 122 msec between the mean response time for correct responses indicated as fast and that for correct responses not indicated as fast, and (2) subjects indicated 1 in 4 correct responses but only 1 in 64 errors. Alcohol increased all response times by approximately 40 msec. In contrast, practice decreased response times less for correct responses not indicated as fast than for correct responses indicated as fast. The ability to distinguish between fast and slow responses was thus unaffected by alcohol, but was improved by practice. Responses indicated as "fast" were significantly faster than errors, and appeared to occur without warning (unlike errors, which tended to end a sequence of increasingly fast correct responses). The results suggest that alcohol and practice influence choice reaction time in qualitatively different ways: Alcohol impairs overall response speed but has no effect on the ability to judge response speed, whereas practice improves both.     

Individual gustatory reaction times to various groups of chemicals that provoke basic taste qualities

Reaction times (RTs) to four groups of substances that provoke different taste qualities were measured. Measurements for all substances with the same taste, equalized in perceived intensity and provoking a very strong taste, were made concurrently for each subject. The comparisons were made on the individual level. No significant differences in RTs to substances with the same taste quality were found. When the factor of perceived intensity is kept constant, no effect of the stimulus chemical composition on RTs seems to be present. RTs to stimuli with different tastes differ significantly, the shortest being to salt and the longest to bitter. The difference in RTs for sour and sweet substances is small, and the subjects were not all alike in terms of the order of RTs with respect to these stimuli.     

Diagnosis and training of basic cognitive performance in children with encephalopathy-typical behavior

This paper reports on the application in practice of a program for diagnosis and basic cognitive achievement training. The program concentrates on performance and its growth in children with encephalopathy-typical behavior. It is demonstrated how deficient cognitive performance may be influenced by level-raising training and transfer effects.     

APPLICANT AGE AND SELECTION INTERVIEW DECISIONS: EFFECT OF INFORMATION EXPOSURE ON AGE DISCRIMINATION IN PERSONNEL SELECTION

Two research questions pertaining to the applicant age bias effect were addressed in this study: the effect of age-related information exposure on selection decisions and the issue of between-sample generalizability with reference to the age bias effect. Manager and student selectors made selection decisions after viewing one videotape of a simulated selection interview of either an old or a young job applicant. Before viewing the interview tape, half of each subject group was given an item of age-related information and the other half was given neutral information. The results showed that, under the neutral information condition, managers preferred hiring the young applicant for the low-status job, and students favored the old candidate for the high-status position. Under the age-related information condition, managers shifted to favoring the old candidate for the low-status job, and students preferred the young applicant for both the low- and high-status positions. Age discrimination in selection decisions and the lack of external validity of student results in selection research are then discussed.     

HIV infection--psychological coping and political reality

The authors warn against a trivialization of the AIDS problem and against the call for state control. Since sexuality is ultimately uncontrollable, they plead instead for the greater clarification of the conflicts which those who are infected with HIV and those who are not infected experience in dealing with each other. The continuing mystification of these conflicts would result in mutual jeopardy through acting-out.     

Threshold tracking for assessment of long-term adaptation and sensitization in pain perception

To assess temporal variations in the perception of "phasic" heat pain stimuli a psychophysical tracking procedure was developed that enables repeated assessment of the pain threshold at short intervals. This "double-tracking" procedure produces two tracking curves simultaneously, one that approaches the pain threshold gradually from above, the other from below. The threshold for phasic heat pain was measured in 80 tracking trials with stimuli at temperatures near the pain threshold. Concurrently, the threshold for "tonic" heat pain was determined after every 20 tracking trials with a stimulus adjustment procedure. Eleven healthy subjects (age: 26.4 yr. +/- 6.0) participated in 2 sessions each. Phasic stimulation near the pain threshold did not produce any trends in either of the two threshold measures. Hence there was no long-term adaptation or sensitization. However, there were random variations (random walks) in the tracking curves, which we interpret as resulting from a stochastic relationship between stimulus and sensation. In agreement with other reports, discrimination seemed to be better at painful than at nonpainful temperatures.     

Distributed and massed practice effects on motor performance and learning of autistic children

The purpose of this study was to examine the effect of massed and distributed practice upon the learning by 8 autistic children of rotary pursuit tracking at 20 rpm. The massed practice group of four completed 10 30-sec. trials with 5-sec. rests for 10 consecutive days on the Photoelectric Pursuit Rotor. The distributed practice group completed 10 30-sec. trials with 30-sec. rests for 10 consecutive days on the same device. The results of a 2 x 10 x 10 (group x practice days x trials) analysis of variance with repeated measures on the last two factors indicated that learning occurred for both groups but no differences between groups were significant. It is suggested that further investigations into the applicability of motor learning principles to special populations be conducted using larger groups.