title: A sequence learning impairment in dyslexia? It depends on the task.
abstract: Language acquisition is argued to be dependent upon an individuals' sensitivity to serial-order regularities in the environment (sequential learning), and impairments in reading and spelling in dyslexia have recently been attributed to a deficit in sequential learning. The present study examined the learning and consolidation of sequential knowledge in 30 adults with dyslexia and 29 typical adults matched on age and nonverbal ability using two tasks previously reported to be sensitive to a sequence learning deficit. Both groups showed evidence of sequential learning and consolidation on a serial response time (SRT) task (i.e., faster and more accurate responses to sequenced spatial locations than randomly ordered spatial locations during training that persisted one week later). Whilst typical adults showed evidence of sequential learning on a Hebb repetition task (i.e., more accurate serial recall of repetitive sequences of nonwords versus randomly ordered sequences), adults with dyslexia showed initial advantages for repetitive versus randomly ordered sequences in the first half of training trials, but this effect disappeared in the second half of trials. This Hebb repetition effect was positively correlated with spelling in the dyslexic group; however, there was no correlation between sequential learning on the two tasks, placing doubt over whether sequential learning in different modalities represents a single capacity. These data suggest that sequential learning difficulties in adults with dyslexia are not ubiquitous, and when present may be a consequence of task demands rather than sequence learning per se.
authors.affiliation: Department of Psychology, University of York, United Kingdom. Electronic address: lisa-marie.henderson@york.ac.uk.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Henderson
authors.affiliation: Department of Psychology, University of York, United Kingdom.
authors.forename: Meesha
authors.initials: M
authors.lastname: Warmington
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D004410:Dyslexia / Q000503:physiopathology* / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D011939:Mental Recall / Q000502:physiology; D011930:Reaction Time; D012691:Serial Learning / Q000502:physiology*; D013647:Task Performance and Analysis; D055815:Young Adult
keywords: Hebb repetition; Sequence memory; Sequential learning; Serial order memory; Serial response time