Elizabeth Gwendolyne Conlon

Preschool Home Literacy Practices and Children's Literacy Development: A Longitudinal Analysis.

In this 3-year longitudinal study, the authors tested and extended M. Senechal and J. Le Fevres (2002) model of the relationships between preschool home literacy practices and childrens literacy and language development. Parent-child reading (Home Literacy Environment Questionnaire plus a childrens Title Recognition Test) and parental teaching of letters, words, and name writing were assessed 6 months prior to childrens school entry. The 143 children (55% male participants; mean age = 5.36 years, SD = 0.29) attended Gold Coast, Australia government preschools. Parent-child reading and literacy teaching were only weakly correlated (r = .18) and were related to different outcomes consistent with the original model. Age, gender, memory, and nonverbal ability were controlled. Parental teaching was independently related to R. W. Woodcocks (1997) preschool Letter-Word Identification scores (R²change = 4.58%, p = .008). This relationship then mediated the relationships between parental teaching and Grades 1 and 2 letter-word identification, single-word reading and spelling rates, and phonological awareness (rhyme detection and phonological deletion). Parent-child reading was independently related to Grade 1 vocabulary (R²change = 5.6%, p = .005). Thus, both home practices are relevant but to different aspects of literacy and language development.

Measuring Visual Discomfort

A two-parameter Rasch Rating Scale model was developed to measure visual discomfort. Initially it was found that participants reporting frequent severe headache, reading difficulties of a visual nature, and short effective reading times experienced more severe visual discomfort. The validity of this measurement instrument was tested in four experiments. In Experiments 1 and 2 reports of unpleasant somatic and perceptual side-effects or ratings of unpleasantness were obtained for low, moderate, and high scorers on the Visual Discomfort Scale. It was found that those with higher scores reported a greater number of unpleasant side-effects and rated square-wave patterns across the spatial frequency range, and a letter pattern as more unpleasant and distorted to view than those with low scores on the scale. In Experiments 3 and 4 these subjective findings were extended to performance. Efficiency was measured using a copying and reading task. It was found that those obtaining high scores on the Visual Discomfor...

Temporal processing in poor adult readers.

The aim of this study was to investigate the relationships between two different temporal processing tasks and word identification performance in skilled, dyslexic and poor adult readers. In Experiment 1 spatial and temporal sequencing tasks were conducted. It was found that adult dyslexics were significantly less accurate than skilled readers across all conditions in the temporal sequencing task, and when higher numbers of stimuli were presented in the spatial task. Experiment 2 replicated Experiment 1 in the temporal sequencing task and also found that poor readers had significantly higher motion coherence thresholds than those found in the skilled reader group. Ten percent of the variance in coherence thresholds was accounted for by performance on the temporal sequencing task. Multiple regression analyses determined that performance on the two temporal tasks could explain seventy percent of the variance in word identification scores, with the temporal sequencing task making the larger independent contribution. Experiment 3 replicated the findings of Experiment 2, while taking into account IQ, verbal memory and processing speed. Three things were concluded. First, the temporal tasks measure different aspects of temporal processing. The contribution to performance of higher-level perceptual and attentional components of the temporal sequencing task accounts for the relatively weak correlation found between the two measures. While sensory sensitivity to motion is measured at MT, the involvement of this area and PPC in higher-level perceptual and attentional processes is suggested by the findings of this study. Second, the association between temporal sequencing and reading skills may provide a stronger link between neural processing and poor reading skills than basic sensory processing measures alone, suggesting that a sensory magnocellular (M) system deficit cannot fully explain the relationship found between reading and visual neural processing. Third, problems with rapid sequential processing are predicted to be a generalised problem in poor adult readers, whether they are formally classified as dyslexic, or are poor performers on measures of word identification. Temporal processing may follow a distribution similar to that found for word identification skills.

Relationships between global motion and global form processing, practice, cognitive and visual processing in adults with dyslexia or visual discomfort

The aim of the first of two experiments was to investigate the effect of practice on sensitivity to global motion and global form in a group of adults with dyslexia, a group of normal readers with visual discomfort, a group with dyslexia and visual discomfort, and a control group. In comparison to the control group, and regardless of the effect of practice, the group with dyslexia was significantly less sensitive to global motion. No differences in global motion sensitivity were found when individuals with dyslexia, with or without visual discomfort, were compared. The normal reading group with visual discomfort was less sensitive to global motion than the control group at baseline, but not when a second estimate of motion sensitivity was obtained. About 30% of the group with dyslexia had a global motion deficit on each threshold estimate. In contrast, there were no significant effects of practice or group on sensitivity to global form. In Experiment 2, performance on a number of cognitive and visual processing tasks was measured in four groups: two with dyslexia; one with and one without a global motion deficit, a normal reading group with visual discomfort, and a control group. The group with visual discomfort had reduced visual processing speed only. Regardless of whether a global motion processing deficit was present or absent in individuals with dyslexia, reduced accuracy was found on the language and visual processing measures, and on a rapid temporal sequencing task. Individuals with dyslexia and a global motion deficit had poorer accuracy than individuals with dyslexia and no motion deficit on the phonological processing and verbal short term memory tasks. We concluded that some adults with dyslexia have a persistent deficit when processing global motion but not global form. This is consistent with reports of a magnocellular pathway deficit in this group. Individuals with visual discomfort do not have a magnocellular processing deficit, but have perceptual difficulties when performing complex visual processing tasks.

The Effects of Visual Discomfort and Pattern Structure on Visual Search

Unpleasant somatic and perceptual side effects can be induced when viewing striped repetitive patterns, such as a square wave or a page of text. This sensitivity is greater in participants with higher scores on a scale of visual discomfort. In three experiments the effect that this sensitivity has on performance efficiency in a reading-like visual search task was investigated. In experiments 1 and 2, the ‘global’ structure of the patterns was manipulated to produce a square-wave, a checkerboard, and a plaid pattern. It was found that the group that suffered severe visual discomfort took significantly longer than other groups to perform the task, with interference greatest with presentation of the square-wave-like pattern. This supports the prediction of greatest distraction of visual attention from the local target elements with presentation of the pattern structure inducing greatest visual discomfort. In experiment 3, the internal pattern components were manipulated and task difficulty reduced. A no-interference and two interference patterns, one with a global characteristic only and the second made up of distracting line elements, containing global and local components were used. The global pattern structure produced interference effects on the visual-search task. All groups performed with the same speed and accuracy on the task involving the no-interference pattern, a finding attributed to reduced task difficulty McConkie and Zolas model of visual attention was used to explain these results.

Auditory and Visual Processing in Children With Dyslexia

This study investigated the temporal stability and longitudinal replicability of visual and auditory sensory processes found to be poor in children with dyslexia. Seventy children with dyslexia and 52 normal readers were tested twice, 9 months apart, on measures of visual and auditory sensory processing and on phonological and orthographic skills. About 30% of children with dyslexia were found to have sensory deficits. Associations were found between sensory and cognitive skills. Based on analyses of agreement, the temporal stability of the sensory tasks was poor. Future research should develop sensory measures with high temporal stability that can control for maturation.

Spatial and Temporal Processing in Healthy Aging: Implications for Perceptions of Driving Skills

ABSTRACT Sensitivity to the attributes of a stimulus (form or motion) and accuracy when detecting rapidly presented stimulus information were measured in older (N = 36) and younger (N = 37) groups. Before and after practice, the older group was significantly less sensitive to global motion (but not to form) and less accurate on a rapid sequencing task when detecting the individual elements presented in long but not short sequences. These effect sizes produced power for the different analyses that ranged between 0.5 and 1.00. The reduced sensitivity found among older individuals to temporal but not spatial stimuli, adds support to previous findings of a selective age-related deficit in temporal processing. Older women were significantly less sensitive than older men, younger men and younger women on the global motion task. Gender effects were evident when, in response to global motion stimuli, complex extraction and integration processes needed to be undertaken rapidly. Significant moderate correlations were found between age, global motion sensitivity and reports of perceptions of other vehicles and road signs when driving. These associations suggest that reduced motion sensitivity may produce functional difficulties for the older adults when judging speeds or estimating gaps in traffic while driving.

Visual discomfort: The influence of spatial frequency

The response of different visual discomfort groups to a range of spatial frequencies at threshold and suprathreshold was investigated. In experiment 1, a paired-comparison task was conducted. The high visual discomfort group judged a spatial frequency of 4 cycles deg−1 as the most perceptually distorted and somatically unpleasant to view. The moderate and low visual discomfort groups judged 8 and 12 cycles deg−1 as more perceptually and somatically unpleasant to view than lower spatial frequencies. In experiment 2, the spatial contrast-sensitivity function (CSF) for the high visual discomfort group was depressed for spatial frequencies between 1 and 12 cycles deg−1 in comparison with the moderate and low visual discomfort groups. When these same spatial frequencies were modulated at 6 Hz, CSFs were the same for all groups. These results are discussed in relation to a failure of inhibition across spatial-frequency channels in the high visual discomfort group. This may be explained by a more generalised parvocellular system processing deficit. Possible similarities between some forms of migraine and visual discomfort are highlighted.

The influence of pattern interference on performance in migraine and visual discomfort groups

Performance in migraine with and without visual aura, non-specific headache and headache-free control groups was measured using a visual search task. Data from groups with high and low visual discomfort were also gathered. No pattern, 2 c/deg, 15 c/deg and a grey field were used in different background conditions. Presentation of patterned backgrounds slowed performance for all groups with the 2 c/deg pattern producing greatest interference. Performance of headache groups did not differ from that of the control group in any condition. The high visual discomfort group responded significantly more slowly than other groups with the 2 c/deg background. It was concluded that the presence of visual discomfort, reported on an everyday basis was a better indicator of heightened sensory sensitivity than the occurrence of migraine with or without aura.

Visual search in migraine and visual discomfort groups.

Two experiments that investigate automatic and conscious attention among migraine and visual discomfort groups are reported. The prediction of a heightened sensory sensitivity producing a processing speed advantage in migraine was tested. In Experiment 1, an automatic attention task was conducted. There was no effect of migraine group, but the high visual discomfort group responded significantly more slowly than the low visual discomfort group when 16 distractors were presented. In Experiment 2, a conscious visual attention task was conducted. No processing-speed advantage was found for migraine groups. In all conditions, the high visual discomfort group performed significantly more slowly than other groups. It was concluded that heightened sensory sensitivity could not explain the processing speed advantage found previously in migraine but may explain the processing speed disadvantage found for the high visual discomfort group. Results are discussed in terms of disordered sustained attention in the high visual discomfort group.