Visual stimuli approaching toward the body influence temporal expectations about subsequent somatosensory stimuli

Visual stimuli in the peripersonal space facilitate the spatial prediction of tactile events-A comparison between approach and nearness effects

Previous studies reported that an object in one's peripersonal space (PPS) attracts attention and facilitates subsequent processing of stimuli. Recent studies showed that visual stimuli approaching the body facilitated the spatial prediction of subsequent tactile events, even if these stimuli were task-irrelevant. However, it is unclear whether the approach is important for facilitating this prediction or if the simple existence of stimuli within the PPS is what matters. The present study aimed to scrutinize the predictive function of visuo-tactile interaction in the PPS by examining the effects of visual stimuli approaching the hand and of visual stimuli near the hand. For this purpose, we examined electroencephalograms (EEGs) during a simple reaction time task for tactile stimuli when visual stimuli were presented approaching the hand or were presented near the hand, and we analyzed event-related spectral perturbation (ERSP) as an index of prediction and event-related brain potentials (ERPs) as an index of attention and prediction error. The tactile stimulus was presented to the left (or right) wrist with a high probability (80%) and to the opposite wrist with a low probability (20%). In the approach condition, three visual stimuli were presented approaching the hand to which the high-probability tactile stimulus was presented; in the near condition, three visual stimuli were presented repeatedly near the hand with the high-probability tactile stimulus. Beta-band activity at the C3 and C4 electrodes, around the primary somatosensory area, was suppressed before the onset of the tactile stimulus, and this suppression was larger in the approach condition than in the near condition. The P3 amplitude for high-probability stimuli in the approach condition was larger than that in the near condition. These results revealed that the approach of visual stimuli facilitates spatial prediction and processing of subsequent tactile stimuli compared to situations in which visual stimuli just exist within the PPS. This study indicated that approaching visual stimuli facilitates the prediction of subsequent tactile events, even if they are task-irrelevant.

Efficient use of peripheral information for temporal prediction

We adapt to the environment by predicting subsequent events. Generally, intervals between predictions and events make it difficult to predict the events accurately. Previous studies reported that using peripheral information is useful for maintaining predictions of subsequent events; however, it remains unclear how this information maintains the accuracy of the prediction. I presented peripheral visual stimuli in a discrimination task and manipulated the number of times these stimuli were presented while participants were waiting for a task-relevant visual stimulus, and compared participants' response times and event-related brain potentials in Experiment 1. In addition, the influence of the difficulty of predicting the task-relevant visual stimulus was examined in Experiment 2. In both experiments, contingent negative variation (CNV) amplitude immediately before the task-relevant visual stimulus appeared was larger under the condition where many peripheral visual stimuli were presented, and the response time was shorter under this condition. In addition, the largest CNV amplitude under this condition was elicited by the third peripheral visual stimulus, followed in order by the first and second peripheral visual stimuli. These results show that we can predict the timing of events that occur with a delay after the prediction by using peripheral information. Moreover, this peripheral information is processed according to the importance of predicting a task-relevant stimulus, and attentional resources are allocated efficiently. These results provide evidence of the predictive function for temporal prediction of using peripheral information and the allocation of cognitive resources.

Approach of visual stimuli facilitates the prediction of tactile events and suppresses beta band oscillations around the primary somatosensory area

The purpose of the present study was to investigate whether the approach of visual stimuli influences prediction of subsequent tactile events. For this purpose, we examined electroencephalograms (EEGs) during the prediction of tactile events when visual stimuli did or did not approach. Tactile stimuli were presented with a high probability (80%) of being applied to the left (or right) index finger and a low probability (20%) of being applied to the opposite index finger. In the approach condition, visual stimuli were presented towards the hand to which the high-probability tactile stimuli were presented; in the neutral condition, visual stimuli did not approach. The result of time-frequency analysis for the EEGs showed that beta band event-related spectral perturbation at the electrodes around the primary somatosensory area (C3 and C4) was suppressed about 300 ms before the presentation of a tactile stimulus and that event-related desynchronization (ERD) occurred in all conditions. Moreover, the beta band ERD of the approach condition was larger than that of the neutral condition. These results provide evidence that the approach of visual stimuli facilitates prediction itself for subsequent tactile events.

Multiple Spatial Coordinates Influence the Prediction of Tactile Events Facilitated by Approaching Visual Stimuli

Interaction with other sensory information is important for prediction of tactile events. Recent studies have reported that the approach of visual information toward the body facilitates prediction of subsequent tactile events. However, the processing of tactile events is influenced by multiple spatial coordinates, and it remains unclear how this approach effect influences tactile events in different spatial coordinates, i.e., spatial reference frames. We investigated the relationship between the prediction of a tactile stimulus via this approach effect and spatial coordinates by comparing ERPs. Participants were asked to place their arms on a desk and required to respond tactile stimuli which were presented to the left (or right) index finger with a high probability (80%) or to the opposite index finger with a low probability (20%). Before the presentation of each tactile stimulus, visual stimuli approached sequentially toward the hand to which the high-probability tactile stimulus was presented. In the uncrossed condition, each hand was placed on the corresponding side. In the crossed condition, each hand was crossed and placed on the opposite side, i.e., left (right) hand placed on the right (left) side. Thus, the spatial location of the tactile stimulus and hand was consistent in the uncrossed condition and inconsistent in the crossed condition. The results showed that N1 amplitudes elicited by high-probability tactile stimuli only decreased in the uncrossed condition. These results suggest that the prediction of a tactile stimulus facilitated by approaching visual information is influenced by multiple spatial coordinates.

Congruency of intervening events and self-induced action influence prediction of final results

Predicting self-induced stimuli is easier than predicting externally produced ones and the amplitude of event-related brain potentials (ERP) elicited by self-induced stimuli is smaller than that elicited by externally produced ones. Previous studies reported that these phenomena occurred strong when stimuli were presented immediately after self-induced action. To be able to adapt to changes, however, it is necessary to predict not only an event that follows a self-induced action but also a subsequent final result. We investigated whether congruency among self-induced actions, intervening events, and final results influences the processing of final results. The congruency of an intervening event with self-induced action was task-irrelevant information for the required response to a final result. The results showed that the P1 amplitude elicited by the final result (i.e., somatosensory stimulus) when an intervening event was congruent with self-induced action was smaller than other elicited amplitudes. This suggests that the congruency of an intervening event and self-induced action may facilitate prediction of a final result, even when this congruency is irrelevant to the ongoing task.