Saturday, March 13, 2010

Neuropsychologia: Lateralised temporal order judgement (TOJ) in dyslexia

ScienceDirect - Neuropsychologia : Lateralized temporal order judgement in dyslexia

In this research study Temporal and Spatial attention deficits in dyslexia were investigated using a lateralised visual temporal order judgment (TOJ) paradigm. This allowed both sensitivity to temporal order and spatial attention bias to be measured.

Findings indicate that adult participants with dyslexia were significantly less sensitive to the temporal order of the stimuli than other adults who were not affected by dyslexia. But this study did not show a significantly different lateral bias.

However, the data indicated that performance on the TOJ task dissociated into at least three factors.

1) The first one loaded on trials with long Stimulus Onset Asynchronies (SOA) and was strongly correlated with full-scale IQ (FSIQ), and, while also correlated with both poor reading and with symptoms of attentional deficit disorder, was not specific to these.

2) The second factor loaded on trials with short SOAs in which the left stimulus was presented first. Low scores on this factor were associated with poor non-word reading accuracy, and factor scores accounted for variance in non-word reading accuracy that was not accounted for by either FSIQ or the presence of a phonological deficit.

This suggests that a “left mini-neglect” syndrome, also reported in attention deficit and hyperactivity disorder (ADHD), may directly contribute to poor non-word reading.

However, attention deficit symptoms loaded not only on this factor, but also on a third factor, representing on trials at short SOAs in which the first stimulus was presented in left hemifield.

This suggests that attentional deficit symptoms impaired temporal processing at short SOAs, regardless of the hemifield in with the stimuli were presented.

The study concludes that people with attention deficits (ADD) find a visual TOJ task difficult when the stimuli are presented rapidly. This is regardless of intelligence levels (FSIQ).

Also, where an attention deficit bias is present, non-word reading accuracy may be directly impaired. This will happen, even if there is no phonological deficit.

For further reading and more scientific papers on Temporal Order Judgement (TOJ) click on this link to Mendeley - Philosophy of the Mind

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