T.M. Horsley

Inhibitory Control During Sentence Reading in Dyslexic Children

The present study focused on the nature of the reading disability of children with the guessing subtype of dyslexia (who read fast and inaccurately). The objective was to separate the excitatory account of their reading disturbance (i.e., in guessers the words’ resting levels of activation are oversensitive to semantic context) from the inhibitory account (i.e., guessers tend to react prematurely to (false) candidate words that are activated in the lexicon). To disentangle the above accounts, guessers and normal readers were presented with a sentential priming task (SPT). In the SPT, subjects had to determine whether the final word of a sentence was semantically congruent or incongruent with the sentence, but had to inhibit their ‘congruent’ or ‘incongruent’ response in case of an occasionally presented pseudoword. To evoke guessing, each pseudoword closely resembled either a valid congruent or incongruent word. Guessing referred to prematurely accepting a pseudoword as a word that either appropriately or inappropriately completed the sentence. The extent to which subjects guessed at word meaning was evidenced by the false recognition rates (FRR) of the misspelled terminal words. Analyses on the FRRs of the pseudowords showed that guessers had significantly more difficulty in suppressing the ‘go tendency’ triggered by the pseudowords. It was concluded that the impulsive reading style of guessers should be ascribed to a less efficient suppression mechanism rather than to excessive reliance on contextual information. Specifically, the data were explained by assuming that the availability of the pseudoword’s candidate meaning activated the hand to respond with, and that guessers found difficulty in suspending this response until they analyzed all letters in the stimulus and they could be sure of its spelling.

The effects of instruction on situation model construction: an eye fixation study on text comprehension in primary school children

This study examined whether the formation of a situation model can be encouraged by a situation‐focused instruction in primary school children. To achieve this, the standard reading‐for‐comprehension instruction was adapted so that it would emphasise the importance of imagination in narrative text comprehension. The results showed that the situational instruction enhanced the situation model construction abilities in good comprehenders in such a way that it improved not only their memory for the situation model but also the ease with which they filled in the gaps in time and space that appeared in the narratives. In poor comprehenders, the situational instruction led to a redistribution of attentional resources allocated to textbase‐ and situation‐level processing. It was suggested that this caused them to go beyond encoding the explicit text and instead construct a situation model from it, and that they did so without enriching the model with general‐knowledge inferences as much as good comprehenders.

Hemispheric differences in stop task performance.

This study examined hemispheric specialization for stop task performance. It was found that inhibitory performance was better for stop signals presented in the right visual field. This result provided support for the hypothesis that, during stop task performance, subjects call upon the left-lateralized neural system that is involved in active attention. It was suggested that a stop task requires such a mode of attention because subjects maintain a tonic readiness for inhibitory action while being engaged in the stop tasks go routine. Subjects are continuously alert for possible stop signals while discriminating between go stimuli. The stop task may be considered a typical activation task.

De ene dyslecticus is de andere niet: Neurocognitief bewijs voor heterogeniteit

Bij dyslexie wordt meestal verondersteld dat er iets mis is met de fonologische verwerking van woorden. Uit onderzoek naar woordherkenning komt echter naar voren dat niet alleen fonologische processen een rol spelen bij het (leren) lezen van woorden. Dit impliceert dat naast defecten in fonologische processen, defecten in andersoortige processen verantwoordelijk kunnen zijn voor dyslexie. Neurocognitief bewijs voor variatie in dyslexie zou uiteindelijk kunnen leiden tot specifiekere en daardoor mogelijk effectievere interventies.