Predicting the Sound-Induced Flash Illusion: A Time-Window-of-Integration Approach

The sound-induced flash illusion (SIFI) refers to the observation that pairing a single flash with 2 auditory beeps leads to the illusory perception of 2 visual stimuli (fission illusion). Susceptibility to the illusion depends on many factors like exact physical stimulus parameters, participants’ expectations, attention, age, and clinical/non-clinical population membership. While there exist many experimental studies, very few models have been proposed to account for the phenomenon. Here we suggest a formal model (SIFI-TWIN) based on the notion of a temporal binding window that predicts the occurrence of illusory flashes as a function of the temporal and physical stimulus arrangement. The model’s performance is illustrated on a study investigating differences in SIFI performance between elderly hearing aid users and those with the same degree of mild hearing loss who were not using hearing aids. The results suggests that the higher incidence of reporting an illusory flash for hearing-aid users is due to both a larger temporal window of integration and a larger bias to report the illusion. The SIFI-TWIN model will help to better understand the diverse results from clinical and non-clinical studies as well as the cognitive foundations of the SIFI.