Abstract:

Inhibition of return (IOR) has been greatly explored in the visual or auditory modality. Investigations on spatial IOR even have extended to the cross-modal link between visual and auditory information processing. The present study examined the generation and variation of IOR effects when targets from the visual and auditory modalities were presented simultaneously (audiovisual targets). In addition, it explored the effect of bimodal divided attention on IOR with audiovisual targets by directing the attention to different modality to form two conditions of attention.
The present study consisted of 3 experiments. In these experiments, we mainly manipulated the target modalities (including visual, auditory, and audiovisual modalities) and cue validities (including cued, neutral, uncued). Thirty-seven college students in Liaoning province were recruited in Exp. 1. The visual (V) target was white horizontal square wave grating (4° × 4°; the spatial frequency was 1 cycle/degree), the auditory (A) target (duration of 100 ms) was a 1000 Hz sinusoidal tone presented by the speakers. The audiovisual (AV) target was composed by the simultaneous presentation of both the visual and the auditory stimuli. During the experiment the fixation stimulus was presented for 800~1000 ms in the center of the monitor. Following the fixation stimulus, uninformative exogenous visual spatial cues were presented between 400~600 ms prior to the onset of targets for 100 ms at the left or right location. Then, the probability of the target (A, V, or AV) appeared for 100 ms in the center was 0.6 (No-go trials), the probability of the target may occur on left or right location was 0.2 (Go trials). The participants were instructed to pay attention to both V and A modalities, then respond to the target stimulus in the left or right location by pressing the response button as quickly and accurately as possible. Thirty-two college students were recruited in Exp. 2. The auditory stimuli were unattended and presented peripherally. Thirty-nine college students were recruited in Exp. 3. The auditory stimuli were unattended and presented centrally, the others were identical to that in Exp. 2.
Based on the results of accuracy (ACC), it can be seen that the overall ACC was very high in Exp. 1. The mean ACC of AV targets was significantly higher than to either V or A targets. According to the results of reaction times (RTs), the mean RT of AV targets were significantly faster than to either V or A targets as expected, indicating the appearance of the bimodal advancement effect. For V targets, the RTs in the cued condition were slower than those in the uncued condition, demonstrated a typical IOR effect. There weren’t IOR effect elicited by AV targets when paying attention to both V and A modalities (Exp. 1). From the results of the relative amount of multisensory response enhancement (rMRE), we found a larger rMRE in the cued condition than that in the uncued condition. In Exp. 2 and Exp. 3, we found the comparable IOR with V and AV targets when the simultaneous auditory stimuli were unattended and presented peripherally or centrally. In addition, we found the comparable rMRE with V and AV targets when the simultaneous auditory stimuli were unattended and presented peripherally or centrally.
These results suggested that the IOR effect elicited by AV targets was reduced when paying attention to multiple modalities. However, when auditory stimuli were unattended, there was no difference between the visual and audiovisual IOR effects. Based on the aforementioned findings, it indicated that bimodal divided attention can influence IOR with audiovisual targets.

Key words: bimodal divided attention, modality-specific selective attention, inhibition of return, audiovisual target, cue-target paradigm