In perception, certain criteria have to be used to select and process stimuli prior to conscious recognition. One possible selection criterion is the color of the stimuli. In previous work it has been shown that color and color selection influence visual event-related potentials (ERP). A frontally localized positivity occurring about 200 ms post stimulus and a more widely distributed negativity from 150 to 350 ms post stimulus have been described. We further explored the mechanisms of color selection with the ERP-technique. The specificity of the effects of color selection and the topographical distribution of the effects by means of isovoltage maps were of particular interest. In two experiments the same 8 healthy subjects viewed a randomized order of stimuli appearing in one of two possible colors. The subjects had the task to attend to stimuli of one color while ignoring those of the other color and to press a button whenever a defined target stimulus appeared in the attended color. Between both experiments the physical aspects of the stimuli varied with respect to form and definition of the target stimuli. This allowed a separation of color-specific and color-nonspecific selection processes. Color specific selection processes have to be independent of physical stimulus aspects, while the effects of nonspecific selection processes vary with the experiments. The earliest effects of color selection on the ERP were found from 200 ms after stimulus presentation. While the latency of the frontal P2-component varied significantly between the two experiments, a superimposed frontal positivity in the range from 200 to 250 ms, which did not vary between the two experiments, could be separated. Also, a more widely distributed negativity between 250 and 500 ms post stimulus was found. While the latency and amplitude of the frontal positivity did not vary between the two experiments, the amplitude of the negativity was significantly larger in one experiment than in the other. These findings are interpreted in terms of a color specific frontal positivity, which is also independent of the P2-component and a color nonspecific negativity. The isovoltage maps showed a frontal maximum for the positivity. These results are discussed with respect to the results of other ERP and Positron Emission Tomography (PET) -studies of color selection.
|Translated title of the contribution||Electrophysiological findings of color selection processes|
|Journal||EEG-EMG Zeitschrift fur Elektroenzephalographie Elektromyographie und Verwandte Gebiete|
|Number of pages||6|
|Publication status||Published - 1995|
Research Areas and Centers
- Academic Focus: Center for Brain, Behavior and Metabolism (CBBM)