Though some studies suggest that older adults are not differentially impacted by foreign-accented speech relative to younger adults, other studies indicate that older adults are poorer at perceiving foreign-accented speech than younger adults. The present study sought, first, to clarify the extent to which older and younger adults differed in their perception of foreign-accented speech. The secondary aim was to elucidate the extent to which the cognitive mechanisms supporting accented speech perception differ for older and younger adults. The data indicated that older adults were poorer at perceiving accented speech than younger adults. Older adults' speech perception accuracy was associated with a significant main effect of working memory as well as significant interactions between hearing acuity and cognitive flexibility and between hearing acuity and inhibitory control. Younger adults' speech perception accuracy, in contrast, was associated with a significant interaction between hearing acuity and processing speed. It therefore appears that the differences in performance between younger and older adults observed here may be attributable to differences in the cognitive mechanisms that support accented speech perception.
The RADD, composed of low-difficulty items from published tests, is rapidly administered, assesses a wide range of cognitive skills and differentiates among all levels of cognitive impairment. The battery has clinical utility with populations exhibiting short attention spans because of its ability to quickly assess a wide range of cognitive abilities. The RADD also has research potential for the documentation of cognitive function in studies of individuals with IDDD.
Although older and younger adults had equivalent performance identifying words produced by talkers with dysarthria, older adults appear to utilize more cognitive support to identify those words.
Background
Individuals with developmental disabilities (DD) often have severe impairments and maladaptive behaviours that make it difficult to reliably assess their cognitive abilities. Given these challenges, the Rapid Assessment of Developmental Disabilities, Second Edition (RADD‐2), was designed to measure general cognitive ability in this population. The purpose of this study is to demonstrate the battery's psychometric properties when used with individuals with DD who have challenging behavioural and psychiatric conditions and for those who have limited verbal skills.
Method
The cognitive and adaptive behaviour skills of 193 children and adults with DD and considerable medical, behavioural and/or psychiatric problems were evaluated using the first and second editions of the RADD, Kaufmann Brief Intelligence Test – 2nd Edition, and Scales of Independent Behaviour – Revised Edition. Medication side effects and challenging behaviours were assessed using the Aberrant Behaviour Checklist.
Results
There were no floor or ceiling effects on the RADD‐2. Both the nonverbal index and total scores had strong concurrent validity with other abbreviated tests of intellectual ability and good discriminant validity from measures of adaptive behaviour and medication side effects. RADD‐2 scores also had strong criterion validity as they successfully differentiated between all levels of intellectual functioning. Age and sex did not differentially affect RADD‐2 performance, and the co‐occurrence of psychiatric conditions did not negatively affect performance. The only medical condition associated with lower RADD‐2 performance was epilepsy.
Conclusions
The RADD‐2 can quantify the differential cognitive abilities of individuals with DD, even for those with minimal communication skills, challenging behaviours or severe medication side effects that can typically complicate assessment. This brief cognitive battery can be used to measure changes due to interventions, on the one hand, and progression of neurological disease, on the other.
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