Suppression of reflexive saccades in younger and older adults: Age comparisons on an antisaccade task

Inhibitory control of prepotent responses has been examined by using the antisaccade task, during which a reflexive saccade toward a peripheral onset must be suppressed before an eye movement in the opposite direction from the onset can be executed. In the present experiments, we sought to determine whether older and younger adults would perform similarly on this task. Older adults had a harder time suppressing their reflexive responses, as measured by an increase in the proportion of saccade direction errors. Despite an age-related decline in saccade direction accuracy, the increase in saccade latency associated with the antisaccade condition was the same for both younger and older adults. These results support the view that the effectiveness of inhibitory control declines with age (Hasher & Zacks, 1988; Hasher, Zacks, & May, 1999).     

Localization of sound in the vertical plane with and without high-frequency spectral cues

Binaural localization of 3.0-kHz high- and lowpass noise presented in the median vertical plane (MVP) and lateral vertical plane (LVP) was investigated. We anticipated superior performance when localizing the highpass noise hy virtue of the availability of pinna cues. The viability of this supposition was strengthened by monaural localization tests in which performance proficiency for the highpass noise exceeded that for the lowpass noise (p < .01). The main result showed that binaural localization of proficiency for highpass noise surpassed that for lowpass noise for all listening conditions (p < .01). However, the importance of binaural temporal and level differences in vertical-plane localization was demonstrated by the highly respectable performances when the lowpass noise was presented in the LVP. Data from binaural localization in the MVP and monaural localization in the LVP suggested that the influence of pinna cues diminishes for source elevations above 45°.     

An experimental investigation into the effects of uncertainty on rational behaviour in two person symmetric games

This paper reports the results of two experiments to investigate the effects of payoff alterations in two-person symmetric games. The initial experiment involved 60 subjects, each of whom could earn from £0 to £15, depending on the interaction of their decisions and the unknown decisions of one other person. All decisions were made without feedback to isolate the impact on subjects' behaviour of the game's parameters. A primary aim was to see if the games had strategically distinct structures, or whether uncertainty over the choice rule of others would influence choice behaviour and lessen this independence. An alternative model of rational choice, making allowance for uncertainty in the decision environment, was proposed to capture subjects' behaviour. The results indicated that the frontiers of most of the games had no impact on choice behaviour other than through the magnitude of the change in payoffs. The model received strong support across an identifiable set of ‘frontierless’ games. However, the variety of games was not sufficient to provide a comprehensive test. A second experiment was recently held to close these gaps. Fifty subjects took part, each of whom earned from A$0 to A$24, averaging A$17. The findings provided broad additional support for the theory.     

Simple geometric fractals

Recently, vision scientists have begun to explore fractals. This paper describes a set of programs that can be used to create fractal and fractal-like drawings. The programs were implemented on the Apple II series of computers. The programs were primarily designed to create deterministic and random fractal-like patterns with fractal dimensionality between 1 and 2. A supplementary program computes the box dimensionality, a measure of dimensionality that does not assume an infinite recursive process. The advantages of this measure of dimensionality over the more typical self-similar measure are discussed.     

Conflict and special service teams: Perspectives and suggestions for school psychologists

Perspectives on the notion of conflict in relation to the functioning of special service teams in public schools are delineated, and suggestions for school psychologists in the area of team conflict management are discussed. Conflict is seen as including both intrapersonal and interpersonal dimensions. Thus, both aspects need to be seen separately and in relation to one another in order to understand conflict situations that affect team functioning. In this regard, intrapersonal and interpersonal conflict can be viewed from social psychological, cognitive-behavioral, organizational, and family systems perspectives. Consideration of these perspectives provides a framework that enables the school psychologist to understant how conflict can be manifested in teams, as well as within the individual team member, and appreciate how diverse factors have the potential to create conflict within teams.     

Comments on Thomas and Jamison's “a test of the X-linked genetic hypothesis for sex differences on Piaget's water-level task”

In this paper H. Thomas and W. Jamison's (Developmental Review, 1981, 1, 274–283) formulation and evaluation of an X-linked genetic model for explaining male superiority on Piaget's water horizontality task is examined. Criticisms are leveled against (1) the suitability of the model invoked for explaining the sex difference found, (2) the power of the statistical test used to evaluate the model, and (3) the appropriateness of their correction factors. A research strategy for advancing our understanding of the sex difference in performance at this task is suggested.     

Selective attention and target search with brief visual displays

In a series of four experiments, subjects were presented with eight item arrays tachistoscopically. In two tasks, the subject was required to recall a digit presented among seven letters or a letter among seven digits. The remaining tasks required the subject to detect the presence of a specific letter either in the context of seven random letters or seven digits. An examination of the effects of a masking stimulus for various target positions suggested that subjects could attend selectively when the target was a different category than its context but had to process the entire array when the target was the same category as the context. The effects of selective attention and masking are explained in terms of parallel and sequential identification processes.     

Predicting Rehabilitation Success with the MMPI and Demographic Data

The purpose of this investigation was to assess the value of selected demographic and personality variables in the prediction of rehabilitation success of handicapped individuals. Demographic data and MMPI scores of 79 clients who had been served by a state Division of Vocational Rehabilitation (DVR) were used as predictor variables in a multiple-regression analysis. An attempt was made to predict three criteria: occupational level, upward mobility, and closure status. The multiple correlations for each of the three regression equations approached significance at the .05 level. Correlations significant at the .05 level, were found between age at onset, age at time of application, type of disability, and education, for one or more of the criteria. Significant beta weights were obtained for age at time of application, IQ, and the Mf, K, and Pd scales from the MMPI.     

Spectral cues which influence monaural Localization in the horizontal plane

An extensive series of behavioral tests was carried out to determine what region, or regions, of the sound spectrum were critical for locating sounds monaurally in the horizontal plane. Seven subjects were requested to locate narrow bands of noise centered at different frequencies, combinations of these noise bands, low-pass, high-pass, and broadband noise. As observed in an earlier study, increasing bandwidth did not necessarily lead to improved localization performance until the band became broad, including, for example, all frequencies above 4.0 kHz. What seems to be happening is that listeners perceive narrow bands of noise originating from restricted places in the horizontal plane which may differ one from another depending on the frequency composition of the stimulus. In several instances, if two noise bands were presented simultaneously, the resulting stimulus was located with reasonable accuracy provided each component, when presented singly, was perceived as emanating from clearly separate azimuthal positions. If, however, two noise bands, which were perceived to originate from approximately the same azimuthal position when presented singly, were now presented simultaneously, the resulting stimulus still was perceived to originate from the same region of the horizontal plane. This, then, is a case where augmenting the spectral content of the stimulus does not bring about improved performance. We suggest that the expression of judgmental biases in the apparent location of a band of noise may prove useful for understanding why some stimuli of specified width and center frequency are localizable while others are not.     

Apparent distance of sounds recorded in echoic and anechoic chambers

With miniature microphones inserted into the external ear canals of a model and the sound source 90 degrees to left of midline, low-pass, and broadband noise bursts were picked up and recorded on magnetic tape. The bursts were generated in two highly contrasting acoustic environments: an anechoic and an echoic chamber. The taped sounds were played back monaurally and binaurally via headphones to 16 listeners seated in an acoustically neutral setting. They were instructed to estimate the distance of the stimuli. Apparent distances of bursts recorded in the echoic or reverberant chamber far exceeded those recorded in the anechoic chamber. It mattered not whether the sounds were presented monaurally or binaurally. What did influence distance estimates dramatically was the frequency composition of the stimuli. Low-pass sounds recorded in either acoustic environment were consistently judged to be further removed than high-pass sounds recorded in the same setting. They were also more likely to appear from behind the listener. In our moment-to-moment transaction with the acoustic environment, distant sounds generally have less acoustic energy in the higher audio frequency. We suggest that this lifetime of auditory experience influenced our listeners' scale of relative distance.