A sample (n=48) of eight-year-olds with specific language impairments is compared with age-matched (n=55) and language matched controls (n=55) on a range of tasks designed to test the interdependence of language and mathematical development. Performance across tasks varies substantially in the SLI group, showing profound deficits in production of the count word sequence and basic calculation and significant deficits in understanding of the place-value principle in Hindu-Arabic notation. Only in understanding of arithmetic principles does SLI performance approximate that of age-matched-controls, indicating that principled understanding can develop even where number sequence production and other aspects of number processing are severely compromised.

The number skills of groups of 7 to 9 year old children with specific language impairment (SLI) attending mainstream or special schools are compared with an age and nonverbal reasoning matched group (AC), and a younger group matched on oral language comprehension. The SLI groups performed below the AC group on every skill. They also showed lower working memory functioning and had received lower levels of instruction.Nonverbal reasoning, working memory functioning, language comprehension, and instruction accounted for individual variation in number skills to differing extents depending on the skill.These factors did not explain the differences between SLI and AC groups on most skills.

No abstract

No abstract

Three experiments are reported, which are based upon the Wason four-card selection task inspection time paradigm, in which subjects solve computer-presented trials while using a mouse to indicate the card currently under consideration. Evans (1996) had shown that selected cards were inspected for longer than non-selected cards, and this was taken as support for the existence of pre-conscious heuristic processes that direct attention towards relevant aspects of a problem. However, Roberts (1998b) suggested that this inspection time effect is artefactual, due to task format induced biases. Experiment 1 utilized a "change" task: Cards were presented either as selected or not selected, and subjects changed these where necessary. This demonstrated an association between card selection and inspection time independently of one between the act of response and inspection time. Experiment 2 utilized a standard selection task, but subjects either responded within 2 s of each card presentation, or made selections with no time pressure. The curtailment of thinking time increased matching behaviour--more cards matching the terms in the rules were selected--and was replicated in Experiment 3 using a within-subjects design. Overall, the data support Evans' heuristic-analytic framework albeit with some caveats.