Color Selectivity of the Spatial Congruency Effect: Evidence from the Focused Attention Paradigm

ABSTRACT

The multisensory response enhancement (MRE), occurring when the response to a visual target integrated with a spatially congruent sound is stronger than the response to the visual target alone, is believed to be mediated by the superior colliculus (SC) (Stein & Meredith, 1993). Here, we used a focused attention paradigm to show that the spatial congruency effect occurs with red (SC-effective) but not blue (SC-ineffective) visual stimuli, when presented with spatially congruent sounds. To isolate the chromatic component of SC-ineffective targets and to demonstrate the selectivity of the spatial congruency effect we used the random luminance modulation technique (Experiment 1) and the tritanopic technique (Experiment 2). Our results indicate that the spatial congruency effect does not require the distribution of attention over different sensory modalities and provide correlational evidence that the SC mediates the effect.

Keywords:

• focused attention paradigm
• multisensory response enhancement
• random luminance modulation technique
• superior colliculus
• tritanopic technique

Notes

1. Mean RTs are presented in the text and figures as values in ms, although all statistical analyses were run on transformed scores (x = 1/RT). Analogously, MRE in the text and figures are values derived from raw RTs in ms, while MRE used in statistical analyses were based on transformed scores.