Note on preference for stimulus complexity across the life-span

Preference for stimulus complexity across the life-span was investigated with 175 females ranging in age from 17 to 72 yr. of age. Preference for complexity appeared to be age-invariant and monotonic function. Relationships to previous findings are discussed.     

Delayed monochromatic hue matches indicate characteristics of visual memory

Short-term memory for 16 monochromatic hues from 425 to 640 nm was measured after six delays from .1 to 24.3 sec by means of an iterative, momentary stimulus-matching technique. Small shifts were revealed in the remembered hue produced by certain wavelengths at some delays. These shifts did not follow trends consistent with a storage dependent on sensory pathway characteristics, perceptually unique hues, or semantic encoding but may reflect entropic effects in a storage that is remarkably unbiased. By indicating the discriminability of hues in memory, standard deviations of the delayed matches reveal other characteristics of what is stored: Their smooth, exponential growth questions the existence of "levels" and permits estimating the half-life of hue memory; their continued resemblance to the discrimination function for simultaneously perceived hues suggests that the stored activity; closely resembled the sensory response of color. The results also indicate how successive comparisons may be corrected in applied color work.     

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.     

The role of attentional resources in automatic detection

The question of whether an automatic detection task requires the use of limited-capacity resources was investigated in a series of dual-task experiments. The automatic task required subjects to detect a consistently mapped target digit in a display of letters. This task was paired with a variety of concurrent visual discriminations that could either occur in close proximity to the automatic target or in a disparate display area. The main finding was that accuracy in each task was higher in conditions allowing attention to be shared than when it had to be divided between separate areas. These results indicate that detection of automatic targets depends on the allocation of spatial attention to the target's area.     

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.