Intersensory Processing Efficiency Protocol (IPEP)

IPEP Description: The Intersensory Processing Efficiency Protocol (IPEP) is a novel protocol designed to assess fine-grained individual differences in the speed and accuracy of intersensory processing for audiovisual social and nonsocial events. It is appropriate for infants (starting at 3 months of age) as well as children and adults. The IPEP is an audiovisual search task requiring visually locating a sound-synchronized target event amidst 5 asynchronous distractor events. Visual attention is typically monitored using an eyetracker. This protocol indexes intersensory processing through 1) accuracy in selection (frequency of fixating the target), 2) accuracy in matching (duration of looking to target), and 3) speed in selection (latency to fixate the target) to social and nonsocial events (see highlight video). IPEP Method: The protocol consists of 48 8-s trials composed of 4 blocks (2 social, 2 nonsocial)—alternating between social and nonsocial blocks of 12 trials each. On each trial, participants view a 3 x 2 grid of 6 dynamic visual events along with a natural synchronized soundtrack to one (target) event. The social events consist of 6 faces of women all reciting different stories using positive affect. The nonsocial events consist of objects striking a surface in an erratic temporal pattern creating percussive sounds. On each trial, the natural synchronized soundtrack to the target face or object is played for 8 s. Trials are preceded by a 3-s attention-getter (looming and contracting smiley face). IPEP Measures: Proportion of total trials on which the target was fixated (PTTF, accuracy in selection), proportion of total looking time to the target (PTLT, accuracy in matching), and latency to fixate the target event (RT; speed in selection) are derived from eyetracking (offline coding schemes are being developed). The highlight video below presents 3 exemplar trials from each condition (social, then nonsocial) in the IPEP with the attention getter preceding each trial. Note: the precision of audiovisual synchrony viewed in these examples may vary depending on internet connection type and available bandwidth and may not reflect the actual temporal synchronies. The full protocol is played using custom-designed Matlab software which interfaces with eye-tracking software (Tobii Studio).