Multisensory perceptual learning is dependent upon task difficulty

Abstract

There has been a growing interest in developing behavioral tasks to enhance temporal acuity as recent findings have demonstrated changes in temporal processing in a number of clinical conditions. Prior research has demonstrated that perceptual training can enhance temporal acuity both within and across different sensory modalities. Although certain forms of unisensory perceptual learning have been shown to be dependent upon task difficulty, this relationship has not been explored for multisensory learning. The present study sought to determine the effects of task difficulty on multisensory perceptual learning. Prior to and following a single training session, participants completed a simultaneity judgment (SJ) task, which required them to judge whether a visual stimulus (flash) and auditory stimulus (beep) presented in synchrony or at various stimulus onset asynchronies (SOAs) occurred synchronously or asynchronously. During the training session, participants completed the same SJ task but received feedback regarding the accuracy of their responses. Participants were randomly assigned to one of three levels of difficulty during training: easy, moderate and hard, which were distinguished based on the SOAs used during training. We report that only the most difficult (i.e., hard) training protocol enhanced temporal acuity. We conclude that perceptual training protocols for enhancing multisensory temporal acuity may be optimized by employing audiovisual stimuli for which it is difficult to discriminate temporal synchrony from asynchrony.

Behavioral Plasticity of Audiovisual Perception: Rapid Recalibration of Temporal Sensitivity but Not Perceptual Binding Following Adult-Onset Hearing Loss

“…Overall, the daily exposure to the training stimuli pairings (e.g., TOJ task: ±200 ms SOA; SJ task: 0 and 200 ms SOA) may have resulted in the rats re-learning the association between the stimuli pairings within their new perceptual state (i.e., impaired hearing sensitivity from hearing loss), which ultimately led to a perceptual recalibration of audiovisual perception. Support for this suggestion comes from previous studies on normal-hearing participants which found that engagement in perceptual training paradigms that included trial-by-trial feedback (like in the present study) led to an improved ability to detect asynchronous audiovisual stimuli, thus resulting in a narrower temporal window of integration (Powers et al, 2009 ; De Niear et al, 2016 , 2018 ). Future studies are needed to determine whether exposure to training stimuli is necessary for the preservation of audiovisual perception.…”

“…It would be reasonable to predict that moderate hearing loss—which reduces one’s sensitivity to environmental sounds—could distort audiovisual temporal acuity due to the fact that varying the intensity (effectiveness) of auditory and/or visual stimuli is known to alter perceptual judgments in normal-hearing participants (Smith, 1933 ; Neumann et al, 1992 ; Neumann and Niepel, 2004 ; Boenke et al, 2009 ; Krueger Fister et al, 2016 ). That said, it is well-established that the perceptual binding of audiovisual stimuli is highly-adaptive to experience, as evidenced from research on participants who were passively exposed to asynchronous audiovisual stimuli (Fujisaki et al, 2004 ; Navarra et al, 2005 ; Vatakis et al, 2007 , 2008b ), as well as those actively engaged in perceptual training (Powers et al, 2009 ; De Niear et al, 2016 , 2018 ). Thus, an alternative prediction could be that individuals who experience adult-onset hearing loss may show limited changes to their audiovisual temporal acuity, owed to a recalibration of their perceptual ability as they adapt to their permanent hearing impairment.…”

Brief Sensory Training Narrows the Temporal Binding Window and Enhances Long-Term Multimodal Speech Perception

“…Surig et al (2018) varied the task difference of a two-alternative forced-choice SJT (either at each participant’s individual threshold or randomly chosen) and discovered faster improvements in the ‘adaptive’ condition regarding the processing speed of auditory inputs as well as the size of the ventriloquist effect. De Niear et al (2016) altered the task difficulty of a SJT and observed that enhancements in temporal acuity could be optimized by employing audio-visual stimuli for which it is difficult to judge temporal synchrony. In another study, De Niear et al (2018) showed that perceptual training was capable of enhancing temporal acuity for simple stimuli (‘flashes’ and ‘beeps’) as well as for more complex speech stimuli (the phoneme ‘ba’).…”

Approaches to Understanding Multisensory Dysfunction in Autism Spectrum Disorder

“…A number of future investigations could evaluate these relationships. Studies have shown that multisensory training paradigms with feedback can result in the narrowing of the TBW and increased functional connectivity between the STS and regions of the auditory and visual cortices in typically developed individuals [De Niear, Gupta, Baum, & Wallace, 2018; De Niear, Koo, & Wallace, 2016; Powers 3rd et al, 2012; Powers, Hillock, & Wallace, 2009]. Work has just begun to investigate if these same paradigms result in improved neural and behavioral multisensory function in individuals with ASD [Feldman et al, 2020], and plan to assess if these effects result in lasting changes to other domains such as social communication.…”

“…parvalbumin‐positive interneurons) are reversibly silenced through optogenetic techniques [Olcese et al, 2013], does this result in impaired social function or the presence of repetitive/restricted behavior? The development of multisensory operant tasks in mice [Meijer et al, 2018; Siemann et al, 2015] also raises the opportunity to evaluate whether training in animal models can improve multisensory function, which may parallel approaches being developed in humans that seek to capitalize on multisensory training [De Niear et al, 2016; De Niear et al, 2018; Powers 3rd et al, 2012; Powers et al, 2009].…”