Evidence for the emotion specificity hypothesis comes primarily from a study by Rojahn, Rabold, et al. (1995). These
authors compared the performance of a group of adults with ID with that of a group of ‘mental age matched’ (i.e. matched on
a measure of cognitive ability) children and a group of adults without ID on an emotion recognition task and a control task
(estimating the age of individuals from pictures). The authors noted that the two tasks had equivalent task demands and only
differed in terms of the cues used to discriminate either emotion or age. They found that the group of adults with ID were
significantly impaired in recognising emotions (happy, sad and neutral expressions) in comparison with the group of mental
age matched controls and that this impairment was not evident on the control task, i.e. recognising if a picture depicted a
person who was young or old.