Misc

We used near-infrared spectroscopy (NIRS) to measure the changes in hemoglobin concentration in the lateral occipital regions during the shape matching and position matching tasks. In the shape matching task, the participants were asked to judge whether successively presented stimuli were identical in shape to the remembered target. In the position matching task, the participants judged whether successively presented stimuli were identical in position to the remembered target. Concentration of oxygenated hemoglobin in the lateral occipital regions was higher for the shape matching task than for the position matching task. This suggests that pronounced activity was present in the lateral occipital regions during shape recognition. The present study, consistent with the former fMRI and PET studies, supports the usefulness of NIRS for monitoring cognitive brain functions.

We measured the hemodynamic responses in the occipital regions during visual stimulation with near-infrared spectroscopy (NIRS). The stimulus was a radial checker pattern (12 deg in radius) of which contrast reversed at 7.5Hz, and was presented to the whole or one quadrant of the visual field. In each measurement session, a 15s stimulating period and a 30s resting period were repeated five times. Hemodynamic changes at the occipital regions were measured with 4×4 probes which were separated from each other by 3cm. The results of the two-session measurements for each visual field showed that oxy-hemoglobin (Hb) concentration increased whereas deoxy-Hb concentration decreased during the stimulating period. Those changes in the Hbs were corresponding to the stimulated visual field, but only when the lower quadrants were stimulated.

Numbers are represented as increasing from left to right in our mental space (mental number line). Here we report two studies which investigated the number-line representation in our mental space. In the first study, we tested how numbers are represented in the depth dimension with using forward/backward vection (illusory self-motion sensation). The results suggest that numbers were represented as they increase from front to back. In the second study, by asking congenital blinds the random number generation task, we examined whether the mental number line is inherently incorporated in our cognitive system. The results suggest that the mental number line was developed via past visual experience.

The present study examined the effect of viewing spatially ordered numbers on time perception. Five single digits were presented as the test stimuli. The digits were chosen from 1 to 9 and presented in a horizontal line. We tested the arrangement of the digits in three conditions, where numerical magnitude of the digits increased from left to right (Small-Large condition), decreased from left to right (Large-Small condition), or in a random order (Random condition). Observers were asked to reproduce the presentation duration of the stimuli by pressing the spacebar for as long as the stimulus had been presented. The results showed that the reproduced time was shorter in the Small-Large condition than the other two conditions. The effect of numerical order on time perception is discussed from the perspective of the mental representation of numbers and fluency of cognitive processing.