Visual Information Can Hinder Working Memory Processing of Speech

Purpose: The purpose of the present study was to evaluate the new Cognitive Spare Capacity Test (CSCT), which measures aspects of working memory capacity for heard speech in the audiovisual and auditory-only modalities of presentation. Method: In Experiment 1, 20 young adults with normal hearing performed the CSCT and an independent battery of cognitive tests. In the CSCT, they listened to and recalled 2-digit numbers according to instructions inducing executive processing at 2 different memory loads. In Experiment 2, 10 participants performed a less executively demanding free recall task using the same stimuli. Results: CSCT performance demonstrated an effect of memory load and was associated with independent measures of executive function and inference making but not with general working memory capacity. Audiovisual presentation was associated with lower CSCT scores but higher free recall performance scores. Conclusions: CSCT is an executively challenging test of the ability to process heard speech. It captures cognitive aspects of listening related to sentence comprehension that are quantitatively and qualitatively different from working memory capacity. Visual information provided in the audiovisual modality of presentation can hinder executive processing in working memory of nondegraded speech material.