Solving the Raven Progressive Matrices by adults with intellectual disability with/without Down syndrome: different cognitive patterns as indicated by eye-movements.

Raven matrices are used for assessing fluid intelligence and the intellectual level of groups with low intelligence. Our study addresses qualitative analysis of information processing in Raven matrices performance among individuals with intellectual disability with that of their typically developed (TD) counterparts. Twenty-three adults with non-specific intellectual disability (NSID), 15 adults with Down syndrome (DS) and 35 children with TD matched for mental age, participated. Participants solved the Raven's Colored Progressive Matrices and five items from the Raven Standard Progressive Matrices while having their eye movements monitored. The overall percent of correct answers was significantly higher for the TD group compared to two ID group. Comparison of the eye movement pattern of each group indicated that the TD group spent more time on the matrices before shifting to the options, than the two ID groups. The TD group made significantly less switches from one rejoins to another, than the ID groups. The difference in the scanning pattern between the TD and the ID groups is interpreted as a reflection of two different types of strategies, Constructive matching and Response elimination, respectively. There were no differences in eye scanning between participants with NSID and those with DS.