Abstract
Previous studies suggest that transient attention favors parvocellular over magnocellular processing. Three studies tested this hypothesis. The first study employed the pulsed-pedestal paradigm (a simultaneous brief presentation of target and pedestals) and the steady-pedestal paradigm (a brief presentation of the target against continuously presented pedestals), whose processing is thought to be mediated by the parvocellular and magnocellular pathways, respectively. Attention was triggered by peripheral precues added to these paradigms. As expected, transient attention improved performance with the pulsed-pedestal paradigm but not with the steady-pedestal paradigm. The second study explored the effects of transient attention on adaptation to spatial frequency and orientation because the parvocellular system processes high frequencies while the magnocellular system processes low frequencies. Two adaptation procedures were employed: one with separated adaptation and test phases and another with intermixed adaptation and test trials. High or low frequency Gabor patches were employed as targets. Peripheral or neutral cues preceded the adaptation displays. There was no attentional manipulation in the test trials. As expected, adaptation effects were increased by transient attention in the high-frequency condition but decreased in the low-frequency condition. The third study examined the effects of transient attention on motion aftereffect (MAE). It was previously demonstrated that adaptation to two superimposed gratings with different spatial frequencies leads to: a) MAE in opposite direction to that of the high frequency grating with a static test stimulus; and b) MAE in the opposite direction to that of the low frequency grating with a flickering test stimulus. Here, attention manipulation was added but only in the adaptation trials. The results reveal an attentional prolongation of MAE when measured with a static stimulus but MAE shortening when measured with a flickering stimulus. The outcome of these three studies can only be explained by an attentional mechanism that favors parvocellular over magnocellular processing.
Meeting abstract presented at VSS 2013