Reaction time to the start and end of weak signals in noise

Summary A theoretical extension of Zwislocki's theory of temporal summation in hearing predicts that the growth of auditory sensation is faster than its decay. Hence the reaction time to the start of a tone ought to be faster than that to its end. Two experiments which investigated this hypothesis are described. Both experiments measured the reaction times of subjects to the start and end of an imperfectly detectable 1000-Hz tone embedded in continuous noise. All three subjects in Experiment I and three of four subjects in Experiment II revealed reaction-time differences in the expected direction; that is to say, the reaction time to the start of the tone was faster than that to its end. One subject in Experiment II did not show this difference, however, and this subject's anomalous behaviour is seen as a qualification to the general nature of the theory.This research was supported by a grant to R.J. Irwin from the Golden Kiwi Scientific Research Distribution Committee and from the University of Auckland     

Effect of head movement on the localization of sounds in the equatorial plane

Five experiments examined the effect of head movement on the localization of sound sources in the equatorial plane. Under most conditions, head movement produces poorer localization for sound sources in the equatorial plane. Only one condition demonstrated an improvement in localization with head movement. The sound source was located toward the side of the head and the source duration was long enough to permit reorientation of the position of the head with re-spect to the sound source.     

A method for clustering eigenvalues

A method of computing communalities is presented which attempts to cluster eigenvalues about zero. Results are exhibited which show reduction of rank using computed communalities.This paper is based on work performed under Contract AF 30(602)-3300 monitored for the U. S. Air Force by Mr. Rocco Iuorno, Rome Air Development Center. The use, under the above contract, of the IBM 7094 computer located at Aeronautical Systems Division, Wright-Patterson Air Force Base, is gratefully acknowledged. Permission is granted for reproduction, translation, publication, use, and disposal in whole and in part by or for the United States Government.     

An area theorem for thesame-different experiment

If observers in a same-different experiment base their decisions on the absolute difference between observations on a trial, the area under the receiver operating characteristic equals the maximum proportion of correct decisions that an unbiased independent-observations observer could attain. Even though the differencing strategy is suboptimal,the area measure yields an index of optimal performance.     

Information integration across saccadic eye movements

The visual world contains more information than can be perceived in a single glance. Consequently, one's perceptual representation of the environment is built up via the integration of information across saccadic eye movements. The properties of transsaccadic integration were investigated in six experiments. Subjects viewed a random-dot pattern in one fixation, then judged whether a second dot pattern viewed in a subsequent fixation was identical to or different from the first. Interpattern interval, pattern complexity, and pattern displacement were varied in order to determined the duration, capacity, and representational format of transsaccadic memory. The experimental results indicated that transsaccadic memory is an undetailed, limited-capacity, long-lasting memory that is not strictly tied to absolute spatial position. In all these respects it is similar to, and perhaps identical with, visual short-term memory. The implication of these results for theories of perceptual stability across saccades are discussed.     

The use of structural equation modeling in generative research: Toward the design of a preventive intervention for bereaved children

Describes a generative study of processes which may lead to symptomatology in children who have experienced the death of a parent. Based on existing literature, four putative mediating variables were identified: parental demoralization, family warmth, negative family events, and positive stable family events. Structural equation modeling techniques were used to compare several potential causal models involving these variables. The results were most consistent with a model in which bereavement was not directly related to the child symptomatology, but rather its effects were transmitted through these four mediational mechanisms. The implications of the results of the structural modeling for the design and evaluation of preventive interventions are discussed briefly.     

Stability and quality of life events and psychological symptomatology in children of divorce

Studied the relations between postdivorce events and maladjustment of children of divorce using a two-dimensional model of events. One dimension concerned the stability of events and included whether they were increases, decreases, or the continuation of stable conditions. The second dimension was quality, and included whether they had a positive or negative valence. Two samples of children of divorce (ns = 142 and 64) ages 8-15 were studied. Children's overall maladjustment as reported by children and parents were the criterion variables. Scores were derived from a life events schedule for children of divorce to assess the occurrence and stability of positive and negative divorce-related events. The relations between event scores and maladjustment were different when children's self-reports and parent reports were used as criterion. In predicting children's self-reported maladjustment (a) stable positive events but not changes in positive events were related to lower maladjustment (b) increased negative events were related to higher maladjustment, and (c) change for the worse was related to higher maladjustment. In predicting parent reports of children's maladjustment, only the relations of the change for the worse score were replicated. Implications of the results for the design of preventive interventions and for the study of children in stressful situations are discussed.