EUN CHO¹ (), Chang-Yeong Han¹, Hyosun Kim², Oh-Sang Kwon¹; ¹Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, ²R&D center, Samsung Display

Transient Twinkle Perception (TTP) is the detection of the frequency transition between two sequentially presented flickering stimuli, which occurs even when the two flickering stimuli appear steady by themselves (Nakajima and Sakaguchi, 2015). A recent study showed that the TTP in luminance flickering stimuli can be explained by applying a biphasic filter model (Han et al., 2023, VSS). Here we investigate the properties of TTP in equiluminant stimuli flickering between red-green colors. In Experiment 1(N=11), we measured the magnitude of TTP in equiluminant red-green flicker stimuli, which changed the frequency from 40Hz to 120Hz. Both 40Hz and 120Hz flickering appear steady by themselves; however, participants experienced TTP. To further characterize the TTP, we inserted ‘in between’ frequency epochs (48, 60 and 80Hz) so that the frequency gradually changes from 40Hz to 120Hz. The numbers of the ‘in between’ frequency frames varied across eight conditions (one to eight). The magnitude of TTP did not increase or decrease monotonically but fluctuated as the frame number of ‘in between’ epochs increased. We applied a biphasic filter model and Gaussian filter model to fit the data. The results showed that the Gaussian filter model fits the data from all participants except one (AIC difference: t(10) = -3.45, p=0.0062). In Experiment 2 (N=4), we directly measured the temporal interaction between two flashing stimuli using Rashbass’ experimental paradigm (1970). We presented red and/or green stimuli successively with varying SOA (11, 18, 27, 36, 43, 52, 68, 77, 94ms) and measured detection threshold. Results showed that the suppressive interaction between flashes are negligible, replicating an existing study (Watson & Nachmias, 1977). The results demonstrate that the temporal processing of equiluminant chromatic stimuli can be explained by applying a monophasic filter model, unlike the luminance stimuli, and the TTP is no exception.

Acknowledgements: This work was supported by the Samsung Display Research Center