Biomedical subjects

John H Hogben

Publications and source records attributed to John H Hogben.

8 recordsLinked to original sources

PubMed2006

Development of auditory saltation and its relationship to reading and phonological processing.

PURPOSE: The temporal offset of auditory saltation is thought to be reflective of the limits of temporal resolution, and has recently been used to compare dyslexic and control adults and children, with mixed results (R. Hari & P. Kiesilä, 1996; M. Kronbichler, F. Hutzler, & H. Wimmer, 2002). This study sought to document and understand normative changes in saltation thresholds as a function of age, and examine the relationship of saltation thresholds to reading and phonological processing across development. METHOD: This study used a cross-sectional developmental design. Groups of 7-8-, 9-10-, and 11-13-year-old children, and adults, undertook a 2-alternative forced-choice saltation task, along with standard tests of reading and phonological processing. RESULTS: Significantly higher and more variable saltation thresholds were evident in the 7-8-year-old group. Group distributions were skewed: Only a few young children obtained poor thresholds while most showed adult-like performance. Saltation thresholds were not related to reading or phonological processing skills at any stage of development. CONCLUSIONS: The temporal offset of saltation is unlikely to reflect the true limits of temporal resolution in young children, but rather the conflation of perceptual and nonperceptual factors (such as poor short-term memory, inattention, and confusion) to task performance. Effort should be made to minimize such nonperceptual factors, particularly when using saltation as a measure of temporal resolution in participants with dyslexia.

Acoustic Stimulation↗

PubMed2005

Poor frequency discrimination is related to oral language disorder in children: a psychoacoustic study.

Some children have difficulty in perceiving differences between sounds, even though they have normal hearing sensitivity, and it has been suggested that such problems could lead to difficulties in language and literacy development. Poor ability to distinguish sounds on the basis of frequency (perceived as pitch) has been described in poor readers on a variety of auditory processing tasks. The aim of the present study was three-fold: to determine whether children with specific language impairment (SLI) have difficulty discriminating frequency, whether this deficit is specific to the frequency domain, or part of a more general auditory impairment, and whether it is linked to reading or oral language ability. The performance of a SLI group (N = 15) and a control group with normally developing oral language matched for age and intelligence (N = 18) was compared on a frequency discrimination task and a control task testing intensity discrimination. The children with SLI consistently demonstrated significantly poorer performance on the frequency discrimination task, but not on the intensity discrimination task. Frequency discrimination thresholds were not related to reading ability in either group. This study provides evidence for a basic auditory deficit in children with SLI, regardless of their reading ability.

Auditory Perceptual Disorders↗

PubMed2004

Cost-effective prediction of reading difficulties.

This study addressed 2 questions: (a) Can preschoolers who will fail at reading be more efficiently identified by targeting those at highest risk for reading problems? and (b) will auditory temporal processing (ATP) improve the accuracy of identification derived from phonological processing and oral language ability? A sample of 227 preschoolers was screened for Performance IQ and was tested on phonological awareness (PA). The upper and lower quartiles of the PA distribution were selected as being at lowest and highest risk, respectively, for reading failure. Children with good and poor PA were tested on ATP, phonological short-term memory, rapid automatized naming, oral language, receptive vocabulary, and 2 measures of listening comprehension. Reading outcomes were measured at the end of Year 2. Only 1 child in the good-PA group became a poor reader by the end of Year 2, confirming that being in the top quartile for PA predicts positive reading outcomes. Discriminant analysis using the authors' test battery within the poor-PA group identified poor readers with sensitivity of.91 and specificity of.84, but ATP did not improve classification accuracy afforded by phonological and oral language. A brief screening procedure was formulated using only PA, phonological short-term memory, and demographic variables, with which 80% of children with poor PA who are at risk of reading problems can be identified. Further refinements of this screening procedure would increase accuracy of identification at the cost of only a small increment in required testing time.

Awareness↗

PubMed2004

The tale is in the tail: an alternative hypothesis for psychophysical performance variability in dyslexia.

Dyslexic groups have been reported to display poorer mean performance than groups of normal readers on a variety of psychophysical tasks. However, inspection of the distribution of individual scores for each group typically reveals that the majority of dyslexic observers actually perform within the normal range. Differences between group means often reflect the influence of a small number of dyslexic individuals who perform very poorly. While such findings are typically interpreted as evidence for specific perceptual deficiencies in dyslexia, caution in this approach is necessary. In this study we examined how general difficulties with task completion might manifest themselves in group psychophysical studies. Simulations of the effect of errant or inattentive trials on performance produced patterns of variability similar to those seen in dyslexic groups. Additionally, predicted relationships between the relative variability in dyslexic and control groups, and the magnitude of group differences bore close resemblance to the outcomes of a meta-analysis of empirical studies. These results suggest that general, nonsensory difficulties may underlie the poor performance of dyslexic groups on many psychophysical tasks. Implications and recommendations for future research are discussed.

Contrast Sensitivity↗

PubMed2004

Attentional modulation of visual processing in adult dyslexia: a spatial-cuing deficit.

Anumber of researchers have suggested that deficient visual attention may play a causal role in dyslexia. However, traditional methods for investigating this assertion have been limited by the conflation of sensory and attentional factors and the inability to isolate large attentional effects. In this study, we sought to overcome these problems by combining spatial cuing with a visual search task measuring psychophysical thresholds. In normal readers, uncued search performance was characterized by a strong dependence on the number of elements in the stimulus array. Cuing the location of the target removed much of this effect, suggesting attentional facilitation of performance. Although dyslexic participants' performance in uncued search was nearly identical to that of normal readers, all dyslexic participants failed to gain the same effect of cuing that normal readers did. However, dyslexic participants did not differ from normal readers on tests of magnocellular function, suggesting that this spatial-cuing deficit is not merely a secondary consequence of magnocellular dysfunction.

Adult↗

PubMed2004

The reliability and validity of tasks measuring perception of rapid sequences in children with dyslexia.

BACKGROUND: Claims that children with reading and oral language deficits have impaired perception of sequential sounds are usually based on psychophysical measures of auditory temporal processing (ATP) designed to characterise group performance. If we are to use these measures (e.g., the Tallal, 1980, Repetition Test) as the basis for intervention in language and literacy deficits, we need to demonstrate that they can effectively quantify individual differences. Therefore, questions of standardisation, reliability and construct validity can no longer be ignored. METHOD: We explored these issues in three studies: (i) 52 Dyslexics and Good Readers aged 8 to 11 years performed a task requiring perception of rapid sequences (PRS) based on the Tallal Repetition Test; (ii) a subgroup of the initial sample was retested on the task three to four months later, and after extended practice; (iii) a further subgroup then completed a rate of auditory processing task using a backward recognition masking paradigm. RESULTS: With a standardised methodology, we were able to replicate previous results with the PRS task, and demonstrate moderate reliability of measurement across time and practice. However, there were large effects of exposure and practice, and the task did not seem useful for identifying absolute and continuing deficits in given individuals. CONCLUSIONS: Our results call into question the use of this type of task as an individual measure of ATP. Neither is it certain that it is capturing what is currently understood as ATP.

Auditory Perception↗

PubMed2004

Quantifying the auditory saltation illusion: an objective psychophysical methodology.

Under conditions of rapid presentation, brief acoustic stimuli repeatedly delivered first at one location, then at another, are systematically mislocalized, with stimuli perceived as traveling smoothly between the two locations. This robust illusory motion percept is termed "auditory saltation." Currently, the characteristics and mechanisms of auditory saltation are not well understood. The lack of objective methods capable of quantifying the illusion on an individual basis seems a limiting factor for this area of research. In this study, we outline an objective psychophysical task that estimates the interstimulus interval at which the saltation illusion is reliably distinguishable from simulated motion. Experiment 1 examined the psychophysical function relating task performance to ISI and addressed the suitability of the task for use with adaptive psychophysical procedures. Experiment 2 directly compared performance on the task with that of another quantification method. The results suggested that this objective approach to the study of auditory saltation overcomes difficulties associated with more subjective methods, and provides a reliable paradigm within which to quantify the temporal parameters of saltation on an individual basis.

Acoustic Stimulation↗

PubMed1985

Suppression of visible persistence.

Five experiments were conducted to examine duration of visible persistence in sequences of stimuli. The basic display consisted of a point that stepped around a circular path on the face of an oscilloscope. Observers estimated the number of points seen simultaneously. Results were compared with a control condition in which the points were plotted in random order rather than sequentially. It was found that visible persistence of a point is suppressed if other points are shown nearby and after an appropriate delay. The degree of suppression depended on the spatial proximity of successive points. It was also found that both duration of visible persistence and degree of suppression increase with eccentricity in the visual field. The results are discussed in terms of two independent processes, persistence and suppression, that operate in a hierarchically antithetical relation.

Figural Aftereffect↗