There appears to be a common network of brain regions that underlie the ability to recall past personal experiences (episodic memory) and the ability to imagine possible future personal experiences (episodic future thinking). At the cognitive level, these abilities are thought to rely on “scene construction” (the ability to bind together multi-modal elements of a scene in mind -dependent on hippocampal functioning) and temporal “self-projection” (the ability to mentally project oneself through time – dependent on prefrontal cortex functioning).
Although ASD is characterised by diminished episodic memory, it is unclear whether episodic future thinking is correspondingly impaired. Moreover, the underlying basis of such impairments (difficulties with scene construction/self-projection/both) is yet to be established. The current study therefore aimed to elucidate these issues.
Twenty-seven intellectually able adults with ASD and 29 age- and IQ-matched neurotypical comparison adults completed a version of a task developed by Hassabis and colleagues (2007). Participants were asked to describe (a) imagined atemporal, non-self-relevant fictitious scenes (fictitious scenes condition), (b) imagined plausible self-relevant future episodes (episodic future thinking condition), and (c) recalled personally-experienced past episodes (episodic memory condition). Tests of narrative ability and theory of mind were also completed.
Performances of participants with ASD were significantly and equally diminished in each condition and, crucially, this diminution was independent of general narrative ability.
Given that participants with ASD were impaired in the fictitious scene condition, which does not involve self-projection, we suggest the underlying difficulty with episodic memory/future thinking is one of scene construction.
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