James H. Smith-Spark

Working memory functioning in developmental dyslexia

Working memory impairments in dyslexia are well documented. However, research has mostly been limited to the phonological domain, a modality in which people with dyslexia have a range of problems. In this paper, 22 adult students with dyslexia and 22 age- and IQ-matched controls were presented with both verbal and visuospatial working memory tasks. Performance was compared on measures of simple span, complex span (requiring both storage and processing), and dynamic memory updating in the two domains. The dyslexic group had significantly lower spans than the controls on all the verbal tasks, both simple and complex, and also on the spatial complex span measure. Impairments remained on the complex span measures after controlling statistically for simple span performance, suggesting a central executive impairment in dyslexia. The novelty of task demands on the initial trials of the spatial updating task also proved more problematic for the dyslexic than control participants. The results are interpreted in terms of extant theories of dyslexia. The possibility of a supervisory attentional system deficit in dyslexia is also raised. It seems clear that working memory difficulties in dyslexia extend into adulthood, can affect performance in both the phonological and visuospatial modalities, and implicate central executive dysfunction, in addition to problems with storage.

Effect of click trains on duration estimates by people with Parkinson's disease.

Patients with a diagnosis of Parkinsons disease and age- and IQ-matched controls estimated the duration of short 500-Hz tones (325–1,225 ms), on trials where the tone was either preceded by 3 s of 5-Hz clicks, or presented without clicks. The click manipulation had been shown in earlier studies with student participants to make verbal estimates longer. Patients were tested both on and off their dopaminergic medication, and controls were also tested in two sessions. Verbal estimates were markedly and significantly longer on trials with clicks than on those without clicks for both the patients and the controls, but there were no significant performance differences between patients or controls, nor between the on and off medication sessions in the patients. The study shows that a manipulation of subjective time, which has had small but consistent effects in student participants, also affects timing in patients and adds to a growing body of evidence that timing in patients with Parkinsons disease may in many cases have the same characteristics as those of neurologically intact control groups.

Everyday cognitive failures and memory problems in Parkinson’s patients without dementia

There is growing evidence that Parkinsons disease patients without dementia exhibit cognitive deficits in some executive, memory and selective attention tasks. However, the impact of these deficits on their everyday cognitive functioning remains largely unknown. This issue was explored using self-report questionnaires. Twenty-four Parkinsons patients and 24 age-matched controls rated how frequently they make particular cognitive errors, such as forgetting what they were about to say. In addition, a partner or significant other also rated each participants propensity for making cognitive errors. Rather than simply rating themselves as making more of all types of errors, these results indicate that PD patients make more of specific types of error. Further analysis suggests that some of these errors are related to attentional processes (being more distractible) whereas others are related to retrieval processes (being unable to recall important details from the previous day).

Executive functions in adults with developmental dyslexia

BACKGROUND Executive functioning (EF) deficits are well recognized in developmental dyslexia, yet the majority of studies have concerned children rather than adults, ignored the subjective experience of the individual with dyslexia (with regard to their own EFs), and have not followed current theoretical perspectives on EFs. AIMS AND METHODS The current study addressed these shortfalls by administering a self-report measure of EF (BRIEF-A; Roth, Isquith, & Gioia, 2005) and experimental tasks to IQ-matched groups of adults with and without dyslexia. The laboratory-based tasks tested the three factors constituting the framework of EF proposed by Miyake et al. (2000). RESULTS In comparison to the group without dyslexia, the participants with dyslexia self-reported more frequent EF problems in day-to-day life, with these difficulties centering on metacognitive processes (working memory, planning, task monitoring, and organization) rather than on the regulation of emotion and behaviour. The participants with dyslexia showed significant deficits in EF (inhibition, set shifting, and working memory). CONCLUSIONS AND IMPLICATIONS The findings indicated that dyslexia-related problems have an impact on the daily experience of adults with the condition. Further, EF difficulties are present in adulthood across a range of laboratory-based measures, and, given the nature of the experimental tasks presented, extend beyond difficulties related solely to phonological processing.

The Representation and Processing of Familiar Faces in Dyslexia: Differences in Age of Acquisition Effects.

Two under-explored areas of developmental dyslexia research, face naming and age of acquisition (AoA), were investigated. Eighteen dyslexic and 18 non-dyslexic university students named the faces of 50 well-known celebrities, matched for facial distinctiveness and familiarity. Twenty-five of the famous people were learned early in life, while the remaining 25 were first encountered more recently. There was no overall difference between the dyslexics and the non-dyslexics in the speed or the accuracy with which they named faces, suggesting that face naming is unimpaired in dyslexic adults. In keeping with previous findings, the results indicated a speed and accuracy advantage for early-acquired over late-acquired faces. In addition, a significant participant group x AoA interaction demonstrated that the non-dyslexic group was significantly faster to name early- than late-acquired faces, while the dyslexic group showed a much smaller and non-significant effect of AoA. The results suggest that there are differences in representation in dyslexia and that these may be linked to problems with attentional/executive function and automaticity. It is proposed that a more fine-grained approach to investigating dyslexia in adulthood should be adopted, in order to uncover cognitive as well as behavioural differences between dyslexics and non-dyslexics.

Stimulus generation, ratings, phoneme counts, and group classifications for 696 famous people by British adults over 40 years of age

Matching stimuli across a range of influencing variables is no less important for studies of face recognition than it is for those of word processing. Whereas a number of corpora exist to allow experimenters to select a carefully controlled set of word stimuli, similar databases for famous faces do not exist. This article, therefore, provides researchers in the area of face recognition with a useful resource on which to base their stimulus selection. In the first phase of the investigation, British adults over 40 years of age were requested to generate the names of famous people (or celebrities) that they thought they would recognize and to write these down. The most frequently named celebrities were then rated by adults from the same age population for familiarity, distinctiveness, and age of acquisition. The result is a database of 696 famous people, with an indication of their relative eminence in the public consciousness and rated for these important variables. Phoneme counts are also provided for each famous person, together with family name frequency counts in the general population, where available. Materials and links may be accessed at www.psychonomic.org/archive.

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.

Do Baseline Executive Functions Mediate Prospective Memory Performance under a Moderate Dose of Alcohol

Prospective memory (PM) is memory for delayed intentions. While deleterious effects of acute doses of alcohol on PM have been documented previously using between-subjects comparisons, the current study adopted a single blind placebo-controlled within-subjects design to explore whether the extent to which alcohol-related impairments in PM are mediated by executive functions (EFs). To this end, 52 male social drinkers with no history of substance-related treatment were tested using two parallel versions of a clinical measure of PM (the Memory for Intentions Test; Raskin et al., 2010), and a battery of EF measures. Testing took place on two occasions, with the order of administration of the alcohol and placebo conditions being fully counterbalanced. Overall, PM was worse under alcohol and participants showed deficits on five of the six subscales making up the clinical test. Hierarchical multiple regression analyses demonstrated that EFs did not predict PM performance decrements overall but did predict performance when time cues were presented and when verbal responses were required. Phonemic fluency was the strongest of the EF predictors; a greater capacity to gain controlled access to information in long-term memory predicted a smaller difference between placebo- and alcohol-related performance on both the time cue and verbal response scales. PM is crucial to compliance with, and response to, both therapy programs and alcohol harm prevention campaigns. The results indicate that individual differences in cognitive function need to be taken into account when designing such interventions in order to increase their effectiveness.

Determinants of famous name processing speed: age of acquisition versus semantic connectedness.

The age of acquisition (AoA) and the amount of biographical information known about celebrities have been independently shown to influence the processing of famous people. In this experiment, we investigated the facilitative contribution of both factors to famous name processing. Twenty-four mature adults participated in a familiarity judgement task, in which the names of famous people were grouped orthogonally by AoA and by the number of bits of biographical information known about them (number of facts known; NoFK). Age of acquisition was found to have a significant effect on both reaction time (RT) and accuracy of response, but NoFK did not. The RT data also revealed a significant AoA×NoFK interaction. The amount of information known about a celebrity played a facilitative role in the processing of late-acquired, but not early-acquired, celebrities. Once AoA is controlled, it would appear that the semantic system ceases to have a significant overall influence on the processing of famous people. The pre-eminence of AoA over semantic connectedness is considered in the light of current theories of AoA and how their influence might interact.