Prospective Memory In Adults With Developmental Dyslexia

While short-term and working memory deficits in individuals with dyslexia are well documented, the effects of dyslexia on prospective memory (PM) have been neglected. A range of PM measures were administered to different samples of university students with and without dyslexia (typically N = 50, 25 per group, matched for age and IQ, and differing on reading and spelling measures). Questionnaire data indicated that individuals with dyslexia perceived themselves as significantly worse on everyday PM activities than non-dyslexics. These data were corroborated by ratings taken from close friends/relatives of the participants. Naturalistic data revealed that adults with dyslexia performed more poorly on a time-based task involving a delay of 40 minutes and 24 hours and an event-based PM task involving a one week delay. There were no event-based PM deficits in dyslexia in the experimental tasks. However, adults with dyslexia were significantly worse at time-based tasks. Difficulties with PM would, therefore, seem to be evident in adults with dyslexia and tend to manifest themselves in time-based PM tasks. This interpretation is consistent with executive functioning problems associated with dyslexia and theories that take a broader view of dyslexia than phonological processing alone

Time-based prospective memory in adults with developmental dyslexia.

Prospective memory (PM) is memory for delayed intentions. Despite its importance to everyday life, the few studies on PM function in adults with dyslexia which exist have relied on self-report measures. To determine whether self-reported PM deficits can be measured objectively, laboratory-based PM tasks were administered to 24 adults with dyslexia and 25 age- and IQ-matched adults without dyslexia. Self-report data indicated that people with dyslexia felt that time-based PM (TBPM; requiring responses at certain times in the future) was most problematic for them and so this form of PM was the focus of investigation. Whilst performing the ongoing task from which they were required to break out every 3 min to make a PM-related response, the participants were allowed to make clock checks whenever they wished. The cognitive demands made on ongoing behaviour were manipulated to determine whether loading executive resources had a mediating role in dyslexia-related deficits in PM, resulting in three tasks with varying working memory load. A semi-naturalistic TBPM task was also administered, in which the participants were asked to remind the experimenter to save a data file 40 min after being given this instruction. Dyslexia-related differences were found across all three computerized tasks, regardless of cognitive load. The adults with dyslexia made fewer correct PM responses and also fewer clock checks. On the semi-naturalistic task, the participants with dyslexia were less likely to remember to remind the experimenter to save the file. This is the first study to document PM deficits in dyslexia using objective measures of performance. Since TBPM impairments were found under more naturalistic conditions as well as on computerized tasks, the results have implications for workplace support for adults with dyslexia

Adults with developmental dyslexia show selective impairments in time-based and self-initiated prospective memory: Self-report and clinical evidence.

BACKGROUND: Prospective memory (PM; memory for delayed intentions) would seem to be impaired in dyslexia but evidence is currently limited in scope. AIMS: There is a need, therefore, firstly, to explore PM under controlled conditions using a broader range of PM tasks than used previously and, secondly, to determine whether objectively measured and self-reported PM problems can be found in the same individuals with dyslexia. METHODS AND PROCEDURES: The responses of 30 adults with dyslexia were compared with those of 30 IQ-matched adults without dyslexia on a self-report and a clinical measure of PM. OUTCOMES AND RESULTS: Dyslexia-related deficits were shown on the clinical measure overall and, more particularly, when PM responses had to be made to cues based on time rather than environmental events. Adults with dyslexia were also more likely to forget to carry out an intention under naturalistic conditions 24h later. On the self-report questionnaire, the group with dyslexia reported significantly more frequent problems with PM overall, despite using more techniques to aid their memory. In particular, problems were identified with longer-term PM tasks and PM which had to be self-initiated. CONCLUSIONS AND IMPLICATIONS: Dyslexia-related PM deficits were found under both laboratory and everyday conditions in the same participants; the first time that this has been demonstrated. These findings support previous experimental research which has highlighted dyslexia-related deficits in PM when the enacting of intentions is based on time cues and/or has to be self-initiated rather than being in prompted by environmental events

Verbal and non-verbal fluency in adults with developmental dyslexia: Phonological processing or executive control problems?

The executive function of fluency describes the ability to generate items according to specific rules. Production of words beginning with a certain letter (phonemic fluency) is impaired in dyslexia, whilst generation of words belonging to a certain semantic category (semantic fluency) is typically unimpaired. However, in dyslexia, verbal fluency has generally been studied only in terms of overall words produced. Furthermore, performance of adults with dyslexia on non-verbal design fluency tasks has not been explored but would indicate whether deficits could be explained by executive control, rather than phonological processing, difficulties. Phonemic, semantic, and design fluency tasks were presented to adults with dyslexia and without dyslexia, using fine-grained performance measures and controlling for IQ. Hierarchical regressions indicated that dyslexia predicted lower phonemic fluency, but not semantic or design fluency. At the fine-grained level, dyslexia predicted a smaller number of switches between subcategories on phonemic fluency, whilst dyslexia did not predict the size of phonemically-related clusters of items. Overall, the results suggested that phonological processing problems were at the root of dyslexia-related fluency deficits; however, executive control difficulties could not be completely ruled out as an alternative explanation. Developments in research methodology, equating executive demands across fluency tasks, may resolve this issue

Self-reports of increased prospective and retrospective memory problems in adults with developmental dyslexia

Short-term and working memory problems in dyslexia are well-documented but other memory domains have received little empirical scrutiny, despite some evidence to suggest that they might be impaired. Prospective memory is memory for delayed intentions, whilst retrospective memory relates to memory for personally experienced past events. To gain an understanding of subjective everyday memory experience, a self-report measure designed to tap prospective and retrospective memory was administered to 28 adults with dyslexia and 26 IQ-matched adults without dyslexia. Adults with dyslexia reported experiencing significantly more frequent problems with memory than the adults without dyslexia. Group differences were found across seven out of the eight questionnaire scales. Further to these analyses, the participants’ own ratings were compared with proxy-ratings provided by close associates. The perception of poorer memory abilities in the participants did not differ between respondent types. The self-reported difficulties are, thus, unlikely to be the result of lowered self-esteem or metacognitive awareness. More frequent difficulties with both types of memory would seem, therefore, to be experienced by adults with dyslexia in everyday life. Further laboratory-based research is recommended to explore both memory domains in dyslexia and to identify the cognitive mechanisms by which these problems occur. The data reported in this paper were collected in partial fulfilment of Adam Zięcik’s PhD at London South Bank University

Retrospective and prospective remembering in adults with developmental dyslexia.

Problems with working memory are well documented in dyslexia, but the impact of dyslexia on other memory systems has been investigated less extensively. Retrospective memory (RM) is memory for personally experienced past events. Prospective memory (PM) is memory for delayed intentions. There is limited evidence to suggest that both RM and PM are impaired in dyslexia and this is focused on children. To expand upon this research, two self-report studies were administered to adults with dyslexia and IQ-matched adults without dyslexia. In Study 1, a questionnaire tapping both RM and PM was completed by respondents and their close associates. More frequent problems with both types of memory were reported by the adults with dyslexia and supported by proxy-ratings. In Study 2, a different sample of participants recorded the errors that they made in their ongoing, naturalistic cognition over a two-week period. More frequent errors relating to both RM and PM were reported by the adults with dyslexia. Responses to the questionnaire and the diary study thus suggest that problems with memory occur more frequently in dyslexia. These findings need to be explained by dyslexia theory and to be fed into the provision of support for people with dyslexia

The event-based prospective memory of adults with developmental dyslexia under naturalistic conditions

Prospective memory (PM) is memory for delayed intentions. Broadly speaking, PM tasks require responses either to events in the environment (event-based PM; EBPM) or at a specific point in time (time-based PM; TBPM). Dyslexia-related deficits in TBPM have been reported under laboratory conditions but group differences in EBPM have yet to be found. However, self-reports suggest that people with dyslexia do experience day-to-day EBPM difficulties. To determine whether EBPM was affected by dyslexia when task demands were more closely related to the demands of everyday life, a task was presented to groups of adults with and without dyslexia, matched for age and short-form IQ. The participants were required to make a response outside the laboratory setting one week after the task had been set. The group with dyslexia were worse at remembering to perform the EBPM task one week later, despite reporting equivalent levels of motivation to perform it successfully. Fewer adults with dyslexia reported remembering the PM instruction at the time it was required. However, they did not differ from adults without dyslexia in the self-reported frequency with which they thought of the PM task over the intervening period. The results suggest that EBPM deficits can be found in dyslexia over longer delay intervals. Dyslexia-related problems with EBPM may relate to the reliable access to verbal information at the point at which it is required. These results are considered in the light of the current understanding of PM impairments in dyslexia