Multi-variate pattern analysis (MVPA) of fMRI signal has been used to investigate cortical mechanisms of human vision. The performance of MVPA is generally more accurate when the number of trials is larger, but the use of a short inter-stimulus interval (ISI) to obtain more trials would cause significant overlap of fMRI responses to multiple events and the isolation of each response could worsen. We investigated this issue using color stimuli (12 hues) presented under shorter- (around 6 s) and longer- (around 15 s) ISI conditions under the same total imaging time. In the waveform analysis using general linear model and deconvolution methods, the goodness-of-fit of mean fMRI response was better in long ISI condition. The positive response trials were found more under long ISI, while negative response trials were found more under short-ISI condition. Although performances of classification into 12 classes with a linear support vector machine were statistically significant above the chance level for both ISI conditions, short ISI condition showed higher performance in early visual areas; this difference disappeared when classified into 5 (i.e., categorical) classes. It implies the presence of different cortical representations across visual areas under same task, together with the advantage of short ISI in the MVPA studies.

A cluster of circular objects can evoke discomfort in observers. On the other hand, as represented by Yayoi Kusama’s works, the cluster of circular objects seems to attract people. In this study, 270 participants were presented with images containing the cluster and were asked to adjust the duration of their observation. After the adjustment task, the participants aesthetically evaluated the images that were observed the longest and the shortest. For the longest observed cluster of circular objects image, we found the following correlation between the viewing time and Interest (r=.35), Intellectual challenge (r=.23), Energy (r=.20), Enchantment (r=.19), Fascination (r=.19), and Joy (r=.19), but the sensitivity of trypophobia (r=-.09). These results suggest that there could be clusters of circular objects which attract interest and make active in observers without triggering trypophobia.

This study investigated the effects of stimulus presentation on CPS and MRS estimates based on viewing style and text measurement methods, aiming to evaluate consistency between CfPS and software-calculated CPS. Thirty-six subjects—12 normal-sighted, 12 low visual acuity, and 12 tunnel vision (with low vision simulation) were analyzed using non-parametric methods. Results showed no significant difference in CPS and MRS between descending and ascending series. CPS was significant between sighted and low vision groups, but MRS was not. CPS estimates and CfPS agreement ranged from fair to good. The ascending sequence method is promising for low vision simulators, unaffected by CPS and MRS estimation.