Motion parallax judgements of depth as a function of the direction and type of head movement

We compared the relative effectiveness of rotating or translating the head, either horizontally or vertically, on the perception of depth resulting from motion parallax. Using Rogers and Graham's (1979) paradigm, we yoked the movement of random dots on a screen to movements of the head, simulating a corrugated surface. In two experiments, subjects nulled the apparent depth or motion seen in the display. Horizontal head movements yielded the most precise depth judgements, irrespective of whether the head translated or rotated. Motion thresholds were higher than those for depth and were independent of direction of head movement. In a third experiment, suprathreshold stimuli that simulated differing amounts of depth were used, and the subjects' perception of depth was virtually the same for all types and directions of head movement. In our stimulus situation, rotating or translating the head either vertically or horizontally produced motion parallax cues for depth that were equally effective. Our results also showed that, within a range, retinal image motion from head movement is converted into a depth signal and that above that range location constancy breaks down and motion is seen.     

The voice of confidence: Paralinguistic cues and audience evaluation

A standard speaker read linguistically confident and doubtful texts in a confident or doubtful voice. A computer-based acoustic analysis of the four tapes showed that paralinguistic confidence was expressed by increased loudness of voice, rapid rate of speech, and infrequent, short pauses. Under some conditions, higher pitch levels and greater pitch and energy fluctuations in the voice were related to paralinguistic confidence. In a 2 × 2 design, observers perceived and used these cues to attribute confidence and related personality traits to the speaker. Both text and voice cues are related to confidence ratings; in addition, the two types of cue are related to differing personality attributes.     

Rhythmic heart rate variability (sinus arrhythmia) related to stages of sleep

Evidence that the excursion of rhythmic heart rate variability (sinus arrhythmia) may be manipulated by altering the subject’s state of concentration, prompted a study of effects associated with different stages of sleep. There were 9 healthy subjects, ages 16–69, and one 55-year-old subject (C.P.) with a myocardial infarction history. Awake and during sleep the excursion of heart rate variability was greatest among the younger subjects, decreasing progressively with age. C.P. displayed rhythmic heart rate variability only when asleep. In light sleep (Stages 1 and 2) all subjects, with the exception of the 69-year-old, whose rate remained almost fixed throughout the night, displayed rhythmic heart rate variability, roughly synchronous with respiration. Neither the elderly subjeot nor C.P. entered into deep sleep (Stages 3 and 4). Among the other subjects, deep sleep was marked by a precise correlation between the frequency of respiration and heart rate variability. In REM sleep, however, in all subjects, there was often a total dissociation between respiration and rhythmic heart rate variability. There were periods of no heart rate variability with continuing regular respiration and of rhythmic heart rate variability with spontaneous breath holding. In the presence of heart rate variability during REM, C.P. displayed frequent ectopic beats, but ectopic beats were nearly absent in REM periods characterized by a steady, unvarying heart rate. The range of heart rate variability at rest and during sleep (sinus arrhythmia) reflects the manner in which autonomic activity is brought to bear in regulating the heart beat. The study of the behavior of sinus arrhythmia may offer a way to anticipate the occurrence of dangerous cardiac dysarrhythmias and sudden death, especially during sleep.     

Achievement Place: development of the elected manager system

A series of experiments was carried out to compare several administrative systems at Achievement Place, a family style behavior modification program for pre-delinquent boys. One aspect of the motivation system at Achievement Place was the token economy in which the youths could earn or lose points that could be exchanged for privileges. Several arrangements for assigning routine tasks and for providing token consequences for task performance were compared for their effectiveness in accomplishing the tasks and for their preference by the boys. The independent variables studied included: (1) individually assigned tasks versus group assigned tasks; (2) consequences for individual performance versus consequences for group performance; (3) a peer managership that could be earned by the highest bidder versus a peer managership that could be determined democratically by the peers. The results suggested that among those systems studied the system that best met the criteria of effectiveness and preference involved a democratically elected peer manager who had the authority both to give and to take away points for his peers' performances.     

Achievement Place: experiments in self-government with pre-delinquents

One of the goals of many treatment programs for pre-delinquent youths is the development of the skills involved in the democratic decision-making process. At Achievement Place, one aspect of the treatment program is a semi-self-government system whereby the seven pre-delinquent youths can democratically establish many of their own rules of behavior, monitor their peers' behavior to detect violations of their rules, and conduct a "trial" to determine a rule violator's guilt or innocence, and to determine the consequences for a youth who violates a rule. Two experiments were carried out to determine the role of some of the procedures in the boys' participation in the self-government system. Experiment I showed that more boys participated in the discussion of consequences for a rule violation when they had complete responsibility for setting the consequence during the trials than when the teaching-parents set the consequence for each rule violation before the trial. An analysis of the rule violations in this experiment indicated that the boys in Achievement Place reported more of the rule violations that resulted in trials than reported by the teaching-parents or school personnel. The boys reported rule violations that occurred in the community and school as well as at Achievement Place, including most of the serious rule violations that came to the attention of the teaching-parents. In Experiment II, the results indicated that more trials were called when the teaching-parents were responsible for calling trials on rule violations reported by the peers than when the boys were responsible for calling trials. When the youths earned points for calling trials the average number of trials per day increased, but more trivial rule violations were reported. These results suggest that aspects of the democratic decision-making process in a small group of pre-delinquents can be studied and variables that affect participation can be identified and evaluated.     

The perception of stop consonants by children

Kindergarten and second-grade children's perception of voicing distinctions among the stop consonants was investigated by assessing their ability to identify and discriminate a series of synthetic speech stimuli varying in voice onset time (VOT). Perception of these sounds was found to be nearly categorical. No differences between the two age groups in either identification or discrimination performance were found; furthermore, the children's performance was comparable to adult performance in other studies using these stimuli. When considered in the context of data on the perception of VOT by infants as well as adults, the results suggest that the differential discriminability of stimuli along the VOT continuum has a biological basis.     

Achievement Place: the reliability of self-reporting and peer-reporting and their effects on behavior

The reliability of the boys reporting their own behavior of their peers was measured in two experiments at Achievement Place, a community based, family style, behavior modification program for delinquents based on a token (point) economy. The results of these experiments indicated that; (a) the boys were not "naturally" reliable observers, (b) the reliability of peer-reporting could be improved by providing training on the behavioral definitions and by making points contingent on agreement between each boy's peer-report and an independent adult observers' report, (c) the reliability of self-reporting could be improved by making points contingent on agreement between the self-report and the trained peer's report, and (d) giving self-reports and peer-reports did not produce a systematic effect on the boys' room-cleaning behavior as measured by an independent observer.     

Modification of articulation errors of pre-delinquents by their peers

Pre-delinquent peers in Achievement Place (a community based family style rehabilitation program based on a token economy) were given points (token reinforcement) to modify the articulation errors of two boys. In Experiment I, using a multiple baseline experimental design, error words involving the /l/, /r/, /th/, and /ting/ sounds were successfully treated by both a group of peers and by individual peers. Also, generalization occurred to words that were not trained. The speech correction procedure used by the peers involved a number of variables including modelling, peer approval, contingent points, and feedback. The individual role of each of these variables was not experimentally analyzed, but it was demonstrated that peers could function as speech therapists without instructions, feedback, or the presence of an adult. It was also found that payment of points to peers for detecting correct articulations produced closer agreement with the experimenter than when they were paid points for finding incorrect articulations. The results were replicated in a second experiment with another subject who had similar articulation errors. In addition, the second experiment showed that peer speech correction procedures resulted in some generalization to the correct use of target words in sentences and significant improvements on standard tests of articulation.     

A comparison of procedures for eliminating self-injurious behavior of retarded adolescents

An attempt was made to eliminate the self-injurious behaviors of four institutionalized, profoundly retarded adolescents. Some of the behaviors studied were: face-slapping, face-banging, hair-pulling, face-scratching, and finger-biting. Three remediative approaches to self-injurious behavior were compared. Elimination of all social consequences of the self-injurious behavior was not effective with the two subjects with whom it was attempted. The same two subjects were exposed to a procedure involving reinforcement of non-self-injurious behavior which was ineffective under no food deprivation and was effective with one of the two subjects under mild food deprivation. Electric-shock punishment eliminated the self-injurious behaviors of all four subjects with whom it was attempted. The results suggested that punishment was more effective than differential reinforcement of non-self-injurious behavior which, in turn, was more effective than extinction through elimination of social consequences. However, the effects of the punishment were usually specific to the setting in which it was administered. In order to eliminate the self-injurious behaviors of severely retarded children, it is apparently necessary to carry out the treatment in many of the settings in which it occurs.     

Human visual motion sensitivity: Evidence against a ratio theory of sensory coding

Luminance thresholds for downward moving contours were measured under several conditions of adaptation. Included was one condition which desensitized visual mechanisms responsive to downward motion. Another condition exerted equal effects on both up- and down-sensitive mechanisms. Thresholds for moving contours were unaffected by exposure to contours which moved in the opposite direction. This indicates that the perception of motion does not depend upon the relative activity in oppositely tuned, directionally selective visual mechanisms.