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Towards a Better Understanding of Working Memory and Filtering Efficiency in Autistic and Non-Autistic Adults
The ability to memorise task-relevant information while filtering out irrelevant information is essential for many tasks in daily life. Recent studies suggest that the amount of information (both visual and auditory) that autistic individuals can process at any given time (perceptual capacity) is increased compared to non-autistic individuals (Remington et al., 2012, 2017). However, it remains unclear if this enhanced processing also persists when visual information must be maintained for a short period of time in working memory, and whether this impacts the efficient filtering of relevant vs. irrelevant information. Here we test this by examining the contralateral delay activity (CDA, Vogel et al., 2005), an electrophysiological (EEG) index in the form of a negative deflection that can be observed during the retention of information in working memory tasks. Importantly, the amplitude of the CDA is modulated by the number of items that are actively maintained in working memory, as well as by the filtering efficiency of the participants.
Objectives:
The current study investigates visual working memory capacity and filtering efficiency by analysing a well-established neural index of (i.e., CDA) on a change detection task.
Methods:
Thirty-six participants (18 autistic and 18 non-autistic adults, data collection ongoing) aged between 18-55 years, took part in the study. The groups were matched on age, gender and IQ, and clinical autism diagnoses were confirmed with the ADOS-2. Brain activity and concomitant CDA was recorded while participants performed a change detection task based on Vogel et al. (2005). For each trial, participants were shown a bilateral visual array consisting of the following items on each side of the visual field: a) two coloured rectangles in the target colour b) four target-coloured rectangles or c) two target and two distractor items (blue rectangles). Participants were asked to memorise the orientation of items in one visual field (cued with a pre-trial arrow) and after 900 ms delay, participants were presented with a test array and indicated whether the orientation of the target items had changed or not. The CDA was averaged for the electrodes over the visual cortex during the memory delay period and the ipsilateral was subtracted from the contralateral activity to establish the activation in response to the target and distractor items.
Results:
The data analysis is ongoing, nevertheless preliminary ANOVAS on EEG amplitude differences between the three conditions revealed no main effect of condition or group (Fs<1)on load an interaction that is trending towards significance (F(2,34)=2.47, p=0.09).
Conclusions:
To our knowledge this is the first study investigating working memory capacity and filtering efficiency in autism using CDA. A better understanding of cognitive control and filtering efficiency may provide fundamental insight into education and workplace experiences, and interventions for autistic individuals.