Objectives: To compare the long-term retention of story details between children and adults with high-functioning autism and typically developing controls.
Methods: Participants included 81 high functioning children with autism (mean age = 11.84, mean VIQ = 103.10, mean FSIQ = 104.68) compared to 32 typically-developing controls, and 48 high-functioning adults with autism (mean age = 26.33, mean VIQ = 105.42, mean FSIQ = 106.38) compared to 67 typically-developing controls. All controls were matched on age, verbal IQ, and full scale IQ. Independent samples t-tests were used to compare memory performance scores on the WRAML for children, and the WMS-III subtests Logical Memory I (immediate recall) and Logical Memory II (delayed recall) for adults. Both test administrations for children and adults included immediate recall of a story followed by a 30 minute delay, as well as a 48 hour delayed recall. Analyses utilized scores based on the total retention of details in the 48 hour delayed recall compared to their 30 minute delay and immediate recall scores. Lower scores indicate greater memory retention.
Results: Analyses of the children’s performance on the WRAML indicate that the autism group retained significantly more details compared to both their 30 minute delay (autism = 0.74, control = 0.96, p<0.01) and immediate recall scores (autism = 0.62, control = 0.86, p<0.001). On the WMS-III, the adults with autism also retained more details than controls. This difference reached statistical significance when 48 hour delay scores were compared to their immediate recall scores (autism = 0.72, control = 0.86, p<0.01), but not compared to their 30 minute delay scores (autism = 0.92, control = 1.00, p>0.05).
Conclusions: The results indicate that individuals with autism demonstrate greater long-term retention of memory for details of stories compared to typically-developing individuals. The result of no difference between the two adult groups when their 48 hour delayed recall scores were compared to their 30 minute delayed recall scores can be explained by a ceiling effect in the overall amount of memory retention by the 30 minute delay. In other words, there was a significantly greater amount of retention in the autism adult group compared to the control group in 48 hour delay versus immediate recall but no difference in the 48 hour versus the 30 minute delay; therefore, the 30 minute delayed recall indicates the point at which there was no additional significant memory loss for both groups.