Asymmetries in the perceptual span for Israeli readers

Native Israeli readers read Hebrew and English text as their eye movements were monitored. A window of text moved in synchrony with their eye movements and the window was either symmetrical about the fixation point or offset to the left or right. When subjects were reading Hebrew, the perceptual span was asymmetric to the left and when they were reading English it was asymmetric to the right. The results point out the importance of attentional factors in reading.     

Letter familiarity does not aid feature extraction

Summary Familiarity effects in visual letter processing were examined by means of a mutilation detection task. The uppercase E was used as the non-mutilated letter. One or two horizontal bars of the E were delected, to produce an upright or inverted F or L. These four mutilations of the E were assigned to the same response. In Experiment 1, brief exposure of the stimuli was followed by a backward mask. Experiment 2 was identical to Experiment 1, except that the display duration of the stimulus was increased and the backward mask was omitted. In Experiment 3, the overall luminance of the stimuli (luminance per point times length of the constituent line segments) was held constant. In Experiment 4, the upright and inverted non-E letter occurred in different blocks to encourage a normal (upright) letter processing strategy in the upright letter blocks. Accuracy (Experiment 1) and mean correct response times (all experiments) were not different for the upright and inverted F or for the upright and inverted L. These findings and converging results from other studies indicate that the higher familiarity of the upright letters did not aid feature extraction.     

Vicarious reinforcement: Expected and unexpected effects

The primary purpose of this study was to examine the effects on one child of observing another child receive direct social reinforcement. In the first part of the study, pairs of same-sex children worked on puzzles for three sessions spaced 2 to 3 days apart. One child was praised on a continuous schedule for performance, whereas the other received no praise. Although children who observed other children being praised increased their performance initially (as predicted by vicarious reinforcement and social comparison hypotheses), their performance decreased over time, reaching levels below their own baseline rates. In the second part of the study, intermittent praise delivered to the observing child was examined as a potential strategy to reverse the unexpected effects obtained in the first part of the study. Intermittent praise was found to be effective in reducing these effects and in producing enhanced performance. Individual data, as well as group data, are presented. Results are discussed in light of theoretical and applied issues related to the use of vicarious reinforcement in applied settings.     

Is visual information integrated across saccades?

After subjects established fixation on a target cross, 12 dots were presented parafoveally. When the dots were presented, the subjects made an eye movement to the location of the dots, and during the saccade the 12 initially presented dots were replaced by 12 other dots. The 24 dots were part of a 5 × 5 matrix, and the task of the subject was to report which dot was missing. The data were consistent with other recent studies: subjects could successfully report the location of the missing dot far above chance (54%), whereas performance in a control condition (in which the two sets of dots were presented to different spatial and retinal locations) was almost at chance level (10%). However, a number of control conditions demonstrated that the effect was due primarily to persistence from the phosphor of the cathode ray tube used for stimulus presentation and that little of the visual information integrated was across two fixations. Implications of the results for a theory of integration across saccades are discussed.     

Enhanced right hemisphere activation in the mathematically precocious: A preliminary EEG investigation

A preliminary electroencephalographic (EEG) investigation was conducted to determine if the pattern of hemispheric activation in mathematically precocious youth differs from that of average math ability subjects. Alpha activity at four brain sites (frontal, temporal, parietal, and occipital lobes) over the left and right cerebral hemispheres (LH/RH) was monitored while 12- to 14-year-old, right-handed males: (a) looked at a blank slide (baseline condition), (b) judged which of two chimeric faces was "happier," and (c) determined if a word was a noun or a verb. At baseline, the LH of the precocious group was found to be more active at all four brain sites relative to that of the average ability group. During chimeric face processing, the gifted subjects exhibited a significant reduction in alpha power over the RH, primarily at the temporal lobe, while no such alpha suppression was observed in the average ability subjects. For noun/verb determinations, no significant alpha power reductions were obtained for either group. These electrophysiological data generally corroborate the behavioral findings of O'Boyle and Benbow (1990a) and support their contention that enhanced RH involvement during cognitive processing may be a correlate of mathematical precocity. Moreover, the pattern of activation observed across tasks suggests that the ability to effectively coordinate LH and RH processing resources at an early age may be linked to intellectual giftedness.     

Minimum rank and minimum trace of covariance matrices

This paper considers some mathematical aspects of minimum trace factor analysis (MTFA). The uniqueness of an optimal point of MTFA is proved and necessary and sufficient conditions for a point x to be optimal are established. Finally, some results about the connection between MTFA and the classical minimum rank factor analysis will be presented.     

Death anxiety, dissent, and competence

A total of 64 male undergraduates were administered a multistage interview which was structured to assess (a) their level of overtly expressed death anxiety, (b) covert (GSR) arousal to death stimuli (c) self-perceived competence, and (d) agreement with or dissent from life threatening national policies. The analyses that followed were concerned with examining the relationships among these variables. In previous studies of this kind it had been typically found that (1) self-perceived competence and magnitude of expressed death concern are inversely related and (2) overt expressions of death concern and covert physiological arousal to death cues are inversely related. Psychodynamic formulations centering on the ego-defensive nature of inhibited expressions of death anxiety have been cited to explain these past data. The current investigation proposed that the magnitude of expressed death concern would bear an inverse relationship to both felt competence and covert death arousal only when the level of overt concern was not contingent upon the individual's attitudes concerning the imminence of real life threatening circumstances in the environment. The rationale behind these predictions inheres in the notion that the neurotic components of strongly expressed death anxiety derive from its lack of anchoring in "real" external threats. Conversely, the expression of low death fear can only be regarded as "defensive" when real threats are perceived and acknowledged. The obtained results strongly support this rationale and the discussion centers on the impact of social conditions on psychodynamic processes.