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Biomedical subjects

D B Boles

Publications and source records attributed to D B Boles.

30 records · Page 2Linked to original sources
PubMed1985

The effects of display and report order asymmetries on lateralized word recognition.

Word recognition typically is better or faster in the right visual field than in the left visual field, an effect that often interacts with the handedness of subjects or the phonetic characteristics of the language employed. While these findings suggest a hemispheric locus, it is possible that the field difference is confounded with display or report order asymmetries. Here two experiments manipulate word orientation (horizontal vs. vertical), letter symmetry, and report order variables, and they demonstrate a generalized right field superiority that fails to interact with other factors. Since the superiority appears even when all apparent artifactual asymmetries are eliminated, the findings support a hemispheric interpretation.

Dominance, Cerebral↗
PubMed1984

Global versus local processing: is there a hemispheric dichotomy?

A major dichotomy proposed for lateralized information processing is that the right and left cerebral hemispheres are "global" and "analytic" processors respectively. Here three experiments employed a tachistoscopic recognition paradigm with letter patterns varying in size and composition. No visual field asymmetries in RT were found in the first two experiments, although statistical power was high and a Stroop-like effect ("global precedence") was supported. Experiment 3 resulted in a right field advantage for vocal naming responses yet no asymmetry for manual responses, suggesting that both hemispheres can recognize global and local patterns, but that introduction of a laterally controlled response independently determines asymmetry.

Adult↗
PubMed1984

Sex in lateralized tachistoscopic word recognition.

Although a generalized sex difference in lateralization appears to be established, a review of the literature pertaining to lexical tachistoscopic tasks suggests a dissociation by method: females show reduced visual field asymmetries relative to males in lexical decision and naming, but not in word recognition. Here 14 recognition experiments from the author's laboratory are subjected to meta-analysis, and the literature review is confirmed. There is no sex difference is visual field asymmetry for the task, although an overall field difference is found and statistical power is high to find the interaction. Possible reasons for the discrepancy with lexical decision and naming findings are discussed. One possibility is that stress on reaction time in those tasks produces a complex interaction between sex, activation/arousal, and hemispheric differences, which is not found when a less speeded method is used.

Adult↗
PubMed1983

Hemispheric interaction in visual field asymmetry.

A survey of previous literature suggests that asymmetries obtained in visual field recognition are larger when stimuli are presented bilaterally than when presented unilaterally. Three experiments confirm the existence of the effect, eliminate a number of published hypotheses used to explain it, and support a mechanism of hemispheric interaction in processing information. Both theoretical and methodological implications are discussed.

Dominance, Cerebral↗
PubMed1983

Visual and phonetic codes and the process of generation in letter matching.

Physically identical letter pairs are matched more quickly than are nominally identical or nonidentical pairs, which is an effect usually interpreted as resulting from the use of a visual memory code versus a phonetic or name code. However, prior manipulations of phonetic confusion and visual-field lateralization have provided little evidence consistent with this notion. Here, three reaction time experiments suggest through converging confusion and visual-field manipulations that a phonetic code is not used in either simultaneous or successive letter matching. Two additional experiments yield confusion evidence consistent with a rapid visual generation process underlying nominally identical and nonidentical matches, emphasizing the role of visual memory processes in all of the commonly used same-different letter-matching tasks. Implications for coding and hemispheric theories are discussed.

Form Perception↗
PubMed1982

Can an analytic/holistic dichotomy explain hemispheric asymmetries?

Same RTs to pairs of letters or other patterns are often faster than different RTs. This finding has led to hypothesize a two-process system of comparison: a fast holistic process for same and a slower analytic process for different responses. In connection with hemispheric specialization, RH has been characterized as a holistic and LH as an analytic processor. Therefore same responses should be mediated by RH and different responses by LH. In the present study, subjects made same-different judgments in the two visual fields to successively presented pairs of letters where degree of difference was systematically varied. RTs decreased with increases in the degree of difference in different responses. Same responses were faster than different. These results suggest analytic processing of different and holistic processing of same pairs. Since no clear-cut visual field superiority was found, the conclusion is that both hemispheres can process visual information analytically and holistically.

Adult↗
PubMed1980

X-linkage of spatial ability: a critical review.

The hypothesis that a major X-linked gene determines spatial ability in man has been cited as an explanation for the adult sex difference in spatial ability. Here the relevant literature is critically reviewed. Early studies often used multiple comparisons, yet repeatedly failed to find significant differences. In some cases the results flatly contradicted the hypothesis, and those results that were consistent with it can be accounted for by chance expectancies. Recent evidence comes from studies that are methodologically superior to the early work; yet these studies provide no support for the X-linkage of spatial ability. It is concluded that belief in the validity of the hypothesis is unfounded.

Adult↗