Doctorat en sciences psychologiques / info:eu-repo/semantics/nonPublished

Two experiments were designed to selectively prime each cerebral hemisphere to evaluate Kinsbourne's selective activation model. The left hemisphere priming manipulation for both experiments was subvocal rehearsal of neutral words, whereas right hemisphere primes consisted of imagery (Experiment 1) and subvocal rehearsal of affective words (Experiment 2). Reaction time performance in the visual field contralateral to the activated hemisphere was hypothesized to improve. No evidence supporting this hypothesis was found in these experiments, though experimental tasks had significant interference effects. In Experiment 1, non-specific interference effects were found across visual fields for both experimental tasks, suggesting the hemispheres were not preferentially recruited. Right visual field interference was observed in Experiment 2 for subvocal rehearsal, particularly of affective words, implicating selective left hemisphere activation. This finding indicates an overloading of the left hemisphere's affective perceptual capabilities. Significantly, no equivalent right hemisphere effects were observed, suggesting different functional space characteristics for affect perception across the hemispheres. These findings appear to substantiate a structural rather than activational model of functional cerebral asymmetries, but interference effects do unequivocally support either model. Furthermore, in Experiment 2, neutral faces were perceived as angry equally often in both visual fields, though neutral faces in the control and affective rehearsal conditions were more frequently perceived as angry relative to the neutral rehearsal condition. Methodological issues are presented to account for these findings. / Master of Science

Eight-letter upper case arrays containing vertically symmetrical (VS), e.g., A-T-U-W, horizontally symmetrical (HS), e.g., B-D-C-E, doubly symmetrical (DS), e.g., H-I-O-X, and non-symmetrical (NS), e.g., F-G-L-R, were tachistoscopically exposed bilaterally for 50 ms. to fifteen male and fifteen female undergraduates. The number of letters correctly recognized for each classification condition was used as the criterion measure. A fixed, two-factor design with the second factor being repeated was analyzed using a repeated measures analysis of variance. Consequent to testing Null Hypothesis 1 (that there is no difference between the classification conditions), a check was made for the presence of a significant interaction between gender and classification condition (Null Hypothesis 2). Because Null Hypothesis 1 was rejected and there was no interaction present, the classification group means were tested using a post hoc multiple comparison procedure identified as Tukey's Honestly Significant Difference (HSD) test. Test statistics for the Tukey HSD contrasts found that significantly more VS letters were reported than DS, HS, and NS letters. Significantly more DS letters were reported than HS and NS letters. No difference in report accuracy was found between HS and NS letters. This is in sharp contrast to studies that count only responses reported in the same left-to-right order as the tachistoscopic presentation, i.e., order of report. Previous studies using an order of report method found vertically asymmetrical letters to be reported more accurately than vertically symmetrical ones. The present study disregarded order of from an order of report. It was emphasized that the subject maintain focus on the fixation dot and not attempt to scan the letter-array pattern in a left-to-right direction, as the lettersdid not have to be reported in their respective positions. A different explanation for the Harcum (1964) directionality and Bryden (1968) masking interpretations follows from an order of report method activating additional processing mechanisms such as working memory that are ordinarily not needed to process letter features.Results obtained by the present study are discussed in terms of a reversal of spatial information for touch, kinesthesis, and sound to match the brain’s reversed retino-cortical projection. / Department of Educational Psychology