Visual Short-Term Memory and Selective Attention in Individuals with Intellectual Disability

Abstract

Individuals with a certain degree of intellectual disability (ID) are widely known for having deficits in some aspects of cognitive functions. This thesis focuses on visuospatial short-term memory (VSTM) and selective attention functions in people with ID compared to typically developed adults (TDA), aiming at the examination of the effect of ID on attentional orienting and visual short-term memory capacity. Participants with and without ID had to perform a simple computerized task, where images were displayed on the screen briefly. Afterwards, they had to recognize if the last image that appeared on the screen was one of the images presented earlier. Valid spatial attentional cues were sometimes presented before (pre - cues) or after (retro - cues) the array, to help individuals with the recognition task and their performance in these trials was compared with performance in neutral cue trials. Additionally, all participants completed the Raven’s 2, a non-verbal intelligence test. Results showed that TDA adults had significantly higher d-prime scores in all conditions (precue neutral/ cued, retrocue neutral/cued) than individuals with ID. Also, TDA had greater attentional benefits than individuals with ID. Furthermore, there were no statistically significant differences between precue and retrocue blocks, neither in cued nor in neutral trials in individuals with ID. These results show that individuals with ID do not benefit from attentional cues to facilitate VSTM capacity. Lastly, correlation analyses indicated positive correlations between intelligence scores and d-prime cued scores as well as intelligence scores and VSTM capacity (Cowan’s K), suggesting that as intelligence scores increase attentional benefits in service of VSTM increase.