1 / 1

Increasing Hemispheric Independence: Bilateral Presentation in Lexical Decision

Increasing Hemispheric Independence: Bilateral Presentation in Lexical Decision. Leonardo Fernandino ¹ , Marco Iacoboni , Eran Zaidel 1 Department of Psychology, University of California, Los Angeles 2 Brain Mapping Center, University of California, Los Angeles 3 Brain Research Institute, UCLA.

nichole-oliver
Télécharger la présentation

Increasing Hemispheric Independence: Bilateral Presentation in Lexical Decision

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Increasing Hemispheric Independence: Bilateral Presentation in Lexical Decision Leonardo Fernandino¹, Marco Iacoboni , Eran Zaidel1 Department of Psychology, University of California, Los Angeles2 Brain Mapping Center, University of California, Los Angeles 3 Brain Research Institute, UCLA 2, 3 1, 3 Introduction • In the normal brain, the two cerebral hemispheres work in close cooperation. In order to study the properties of each hemisphere alone, it is desirable to create conditions that reduce this cooperation to a minimum by maximizing hemispheric independence. • We investigated the effects of bilateral presentations in lateralized lexical decision to test the hypothesis that a distractor presented to the visual hemifield contralateral to the target would increase hemispheric independence. The condition of maximal independence allows for a better measure of left hemisphere specialization for word recognition. • A previous experiment with mixed unilateral and bilateral stimuli found an increase in hemispheric specialization for targets presented with distractors (Iacoboni & Zaidel, 1996). In the present study, unilateral and bilateral stimuli were blocked rather than mixed. Method Participants: 83 right-handed UCLA undergraduates. Stimuli: strings of letters presented to the left and/or to the right of a central fixation cross. Task: to decide whether or not the underlined letter string is a word by pressing the corresponding keys bimanually on the keyboard. Stimuli were presented for 120ms. Unilateral and bilateral trials were presented in separate blocks, with 120 trials each. Results • The presence of a distractor contralateral to the target affects the processing of words and nonwords in different ways, increasing the right visual field advantage for words, but not for nonwords. This accentuates the dissociation between the two visual fields observed in unilateral presentations. • With bilateral presentations, the right visual field advantage (RVFA) for words increases, but the RVFA for nonwords is reversed. The overall RVFA remains the same as in unilateral presentations. Conclusions • These results indicate that bilateral presentations make processing within each hemisphere more independent from the other, providing more adequate conditions for the study of hemispheric function. • This increase in independence was not accompanied by an increase in the overall RFVA, i.e., left hemisphere specialization. • By contrast, Iacoboni & Zaidel (1996) found a greater RVFA with bilateral than unilateral presentations, with both conditions mixed within blocks. In the present study, the increase in hemispheric independence due to the blocking of conditions counteracted the change in the overall RVFA. Reference: Iacoboni, M & Zaidel, E. (1996). Brain and Language, 53, 121-140. Example: + horse hand + life Unilateral Bilateral Contact: fagundes@ucla.edu

More Related