Intra-Individual Reaction Time Variability in Mild Cognitive Impairment and Alzheimer’s Disease: Gender, Processing Load and Speed Factors

Compared to cognitively healthy ageing (CH), intra-individual variability in reaction time (IIV(RT)), a behavioural marker of neurological integrity, is commonly reported to increase in both Alzheimer’s disease (AD) and mild cognitive impairment (MCI). It varies in MCI with respect to whether it represents the pro-dromal stages of dementia or not; being greatest in those most likely to convert. Abnormal IIV(RT) in MCI therefore represents a potential measure of underlying functional integrity that may serve to differentiate MCI from CH and to help identify those patients for whom MCI is the result of a progressive pathological process. As the clinical approach to MCI is increasingly stratified with respect to gender, we investigated whether this factor could influence study outcome. The influence of RT(SPEED) and processing load upon IIV(RT) was also examined. Under low processing load conditions, IIV(RT) was significantly increased in both MCI and AD compared to CH. However, correcting for an individual’s processing speed abolished this effect in MCI but not in AD, indicating that the increased IIV(RT) in MCI and AD may result from different factors. In MCI but not in CH, IIV(RT) was significantly greater for females. Increasing task processing load by adding distracting information, although increasing overall IIV(RT), failed to improve the differentiation between CH and both MCI and AD, and in MCI resulted in a reduction in the influence of gender upon study outcome. The outcome of studies investigating IIV(RT) in MCI and AD compared to CH therefore appear influenced by the gender of the participants, by task-related processing load and processing speed

How to present more readable text for people with dyslexia

The presentation of a text has a significant effect on the reading speed of people with dyslexia. This paper presents a set of recommendations to customize texts on a computer screen in a more accessible way for this target group. This set is based on an eye tracking study with 92 people, 46 with dyslexia and 46 as control group, where the reading performance of the participants was measured . The following parameters were studied: color combinations for the font and the screen background, font size, column width as well as character, line and paragraph spacings. It was found that larger text and larger character spacings lead the participants with and without dyslexia to read significantly faster . The study is complemented with questionnaires to obtain the participants’ preferences for each of these parameters, finding other significant effects. These results provide evidence that people with dyslexia may benefit from specific text presentation parameters that make text on a screen more readable. So far, these recommendations based on eye tracking data are the most complete for people with dyslexia