The modulation of simple reaction time by the spatial probability of a visual stimulus

Autor(es)

L.R.R. Carreiro ^[1] ; H. Haddad Jr. ^[2] ; M.V.C. Baldo ^[3]

Afiliação do(s) autor(es)

^[1] Universidade de São Paulo. Instituto de Ciências Biomédicas I. Departamento de Fisiologia e Biofísica - Brasil

^[2] Universidade de São Paulo. Instituto de Ciências Biomédicas I. Departamento de Fisiologia e Biofísica - Brasil

^[3] Universidade de São Paulo. Instituto de Ciências Biomédicas I. Departamento de Fisiologia e Biofísica - Brasil

• Tipo de documento: Artigo Científico
• Fonte: Brazilian Journal of Medical and Biological Research; v. 36, n. 7, p. 907-911, 2003-07-00.

Resumo

Simple reaction time (SRT) in response to visual stimuli can be influenced by many stimulus features. The speed and accuracy with which observers respond to a visual stimulus may be improved by prior knowledge about the stimulus location, which can be obtained by manipulating the spatial probability of the stimulus. However, when higher spatial probability is achieved by holding constant the stimulus location throughout successive trials, the resulting improvement in performance can also be due to local sensory facilitation caused by the recurrent spatial location of a visual target (position priming). The main objective of the present investigation was to quantitatively evaluate the modulation of SRT by the spatial probability structure of a visual stimulus. In two experiments the volunteers had to respond as quickly as possible to the visual target presented on a computer screen by pressing an optic key with the index finger of the dominant hand. Experiment 1 (N = 14) investigated how SRT changed as a function of both the different levels of spatial probability and the subject's explicit knowledge about the precise probability structure of visual stimulation. We found a gradual decrease in SRT with increasing spatial probability of a visual target regardless of the observer's previous knowledge concerning the spatial probability of the stimulus. Error rates, below 2%, were independent of the spatial probability structure of the visual stimulus, suggesting the absence of a speed-accuracy trade-off. Experiment 2 (N = 12) examined whether changes in SRT in response to a spatially recurrent visual target might be accounted for simply by sensory and temporally local facilitation. The findings indicated that the decrease in SRT brought about by a spatially recurrent target was associated with its spatial predictability, and could not be accounted for solely in terms of sensory priming. (AU)

• Processo FAPESP: 96/06618-9 - Estudo de mecanismos atencionais e pre-atencionais envolvidos na percepcao visual.
• Beneficiário: Marcus Vinícius Chrysóstomo Baldo
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 99/07382-7 - Estudo do efeito de diferentes mecanismos de orientação da atenção visual sobre o tempo de reação manual
• Beneficiário: Luiz Renato Rodrigues Carreiro
• Modalidade de apoio: Bolsas no Brasil - Doutorado