Presentation for 2006 Meeting of the Society for Neuroscience
Visual and auditory short-term memory are highly similar when examined with comparable stimuli and identical tasks: Comparing apples to apples
How similar are the information processing steps that produce short-term memories from different senses, particularly vision and audition? Since visual and auditory information arise from different sensory organs and are processed over different pathways, discrepancies in their associated memory processes would not be surprising, and have been claimed by various studies. However, to date no fair, apples-to-apples comparison of short-term memory formation from visual and auditory stimuli has been conducted. Such a comparison requires stimuli with early sensory processing that is as similar as possible. In addition, a fair comparison requires that identical methods be tested on the same subjects, and, to avoid spuriously similar results, that tests minimize the role of verbal mediation.
To satisfy these requirements, we compared memory for sinusoidal visual gratings with memory for ripple sounds, auditory stimuli whose early cortical processing is analogous to that for sinusoidal visual gratings (Shamma, 2001). A within-subjects design made use of Sternberg's (1966) recognition memory paradigm. On each trial, a sequence of stimuli (varying in speed of moving ripple sounds, speed of moving visual gratings, or spatial frequency of static visual gratings) was followed by a probe stimulus. Subjects judged whether the probe matched any sequence item. To equalize task difficulty across subjects and stimulus types, we equated differences between stimuli within each type based on an individual subject's just noticeable difference threshold for that stimulus type.
Responses to all three stimulus types showed strong, highly similar effects of load (number of remembered items), and minimal effects of retention interval length (to ~10 sec). The absence of differences among stimulus types demonstrates that information processing for shortterm memory is quite similar for auditory and visual stimuli. This outcome is consistent with the hypothesis that the common processing goals and similar neural architectures of the two senses produce similarities in short-term memory. These similarities could arise from similar circuitry in different brain areas, or from shared processing units across the two domains.
Supported by NIH grants MH068404.