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Reading is a multisensory process, one that involves the rapid and precise integration of both auditory and visual information. Integrating multisensory information requires temporal processing skills, in order to accurately perceive and coordinate the different types of sensory stimuli. Research has shown that individuals with dyslexia tend to perform more poorly in tasks that require temporal processing, even when the stimuli is non-linguistic in nature (e.g. ‘beeps’ or ‘flashes’ or even tactile ‘buzzes’). The temporal binding window (the window of time within which nonsimultaneous information is perceived as being simultaneous) has been shown to be altered in individuals with certain developmental disorders, including dyslexia, offering a possible explanation for the temporal processing deficit that is hypothesised to be at the root of dyslexia.
In order to investigate this further, a study was conducted with the aim of building a comprehensive profile of crossmodal temporal processing in adult readers with dyslexia. The temporal processing skills of thirty Irish university students (14 with dyslexia and 16 controls) were measured using two simultaneity judgment tasks involving Audio-Visual, Audio-Tactile and Visual-Tactile information. Visual stimuli were presented on a computer screen, auditory stimuli were heard through a speaker and tactile stimuli were presented using a vibro-tactile stimulator to participants’ finger. Finally, participants completed a short tapping task that required their synchronising with a beat produced by an external metronome.
Overall, it was found that the participants with dyslexia were significantly less accurate at identifying and actively producing simultaneity than the control group, although this difference was not significant for each task and each modality. These findings support the theories that propose a crossmodal temporal processing deficit is central to dyslexia. Fortunately, research evidence has shown that temporal processing skills can be quickly and effectively improved using training that narrows the temporal binding window. These training methods may be more effective at helping people with dyslexia to overcome the disorder, than interventions that focus only on literacy skills.