Heart rate differences between targets and non targets in intuition tasks.

This study reports the results of one experiment and a replication, aimed at investigating heart rate changes related to a pure intuition task. In each experiment, twelve subjects were required to guess which of the four pictures presented in sequence for about 10 seconds, was the target. Each subject performed 20 trials. In each trial the target was automatically selected using a pseudo-random algorithm. Heart rate was recorded (see Method section for details) during the pictures presentation. In the first experiment, a statistical significant increment of heart rate associated to targets with respect non targets was observed. The replication experiment with new twelve subjects confirmed the data obtained in the main experiment. These findings support the hypothesis that heart rate is related not only to overt but also to covert cognitive activity such as that involved in intuition tasks, giving convergent evidence to the models describing our intuitive cognitive activity as a double, partial independent information processing system.

The development of reading speed in Italians with dyslexia: a longitudinal study.

The development of reading speed in Italian children with dyslexia was estimated using individualized growth curves for a group of 38 children with dyslexia tested longitudinally from the second to the eighth grade and compared with typical readers. Their reading speed development followed a linear trend of .3 syllables per second per grade, approximately half the increment observed in typical children reading a passage and similar to typical children's reading of nonword lists. These findings give support to the deficit hypothesis versus the lag hypothesis and to reading speed as the core deficit in dyslexia with transparent orthographies.

Treatment of specific developmental reading disorders, derived from single- and dual-route models.

A group of 21 participants with specific reading disorders was treated with a method derived from dual-route models and another group of 23 with a method derived from single-route models of reading. Both treatments were compared with four control treatments. The reading performance of each participant was compared with that of his or her chronological-age controls on the following variables: speed and accuracy of reading passage, isolated words and nonwords, and accuracy in homophone recognition. The treatment deriving from dual-route models produced significant improvements in the homophone recognition, compared to all other treatments. The treatment deriving from single-route models produced significant improvements, compared to all other treatments, in speed of word reading. Furthermore, these two treatments produced significant improvement with respect to all other treatments but one, in speed of nonword reading. These findings support the hypothesis that treatments derived from specific models of reading development are superior to other treatments. However the benefits obtained on the reading of isolated stimuli (words, homophones) did not significantly improve the reading of a passage. This fact suggests that treatments should include exercises involving passages or sentences.

Imagery deficits in nonverbal learning disabilities.

This study reports the observations gathered from 11 children referred to consulting services because of learning difficulties at school and diagnosed with nonverbal learning disabilities (NVLD). These children had an average verbal IQ, but a WISC-R performance IQ lower than the verbal IQ by at least 15 points and experienced difficulties especially in mathematics and drawing. The children completed a battery of four tasks requiring visuospatial working memory and visual imagery: a memory task composed of pictures and their positions (Pictures task), a task that required them to memorize the positions filled in a matrix (Passive Matrix task), a task that required them to imagine a pathway along a matrix (Active Matrix task) and a task that required them to learn groups made up of three words, using a visual interactive imagery strategy (TV task). In comparison to a control group of 49 children, children with NVLD scored lower in all the tasks, showing deficits in the use of visuospatial working memory and visual imagery. By contrasting subgroups of children of different ages in the control group, it was possible to show that some tasks did not show a clear developmental trend. Thus the deficits shown by the children with NVLD cannot simply be attributed to a developmental delay of these children, but seem to reflect a more severe disability.

Visual selective attention and reading efficiency are related in children.

We investigated the relationship between visual selective attention and linguistic performance. Subjects were classified in four categories according to their accuracy in a letter cancellation task involving selective attention. The task consisted in searching a target letter in a set of background letters and accuracy was measured as a function of set size. We found that children with the lowest performance in the cancellation task present a significantly slower reading rate and a higher number of reading visual errors than children with highest performance. Results also show that these groups of searchers present significant differences in a lexical search task whereas their performance did not differ in lexical decision and syllables control task. The relationship between letter search and reading, as well as the finding that poor readers-searchers perform poorly lexical search tasks also involving selective attention, suggest that the relationship between letter search and reading difficulty may reflect a deficit in a visual selective attention mechanisms which is involved in all these tasks. A deficit in visual attention can be linked to the problems that disabled readers present in the function of magnocellular stream which culminates in posterior parietal cortex, an area which plays an important role in guiding visual attention.

Visuo-spatial working memory limitations in low visuo-spatial high verbal intelligence children.

Visuo-spatial working memory was investigated in a group of 37 children aged between 10 and 14 years with low visuo-spatial intelligence. Their performance was poorer than that of a matched control group on a series of tests devised to ascertain visuo-spatial working memory yet was broadly similar in a language test and in school achievement tests. It is argued that low visuo-spatial intelligence children typically present limitations in the storage capacity of a passive system of the visuo-spatial working memory (with a raw measure of four-five stored elements) and especially in the operations required to process that information.

Visual evoked potentials related to behavioral asymmetries during foveal attention in the two extrapersonal hemispaces.

In a group of male and female subjects we studied the VEPs related to the solution of a lexical decision task presented in the Left and Right Hemispaces with respect to the Central position in order to explore the electrophysiological correlates of the performance asymmetries obtained when overt spatial attention is directed to the Left or Right Hemispace. When stimuli were presented in the Left Hemispace a significant asymmetry was observed between the two hemispheres of the negative activity around 280 msec in the occipital-parietal areas. Moreover a general increase in the Central and Frontal areas of both the hemispheres was observed. In this paper we discuss why these effects can be considered to be the cause of the costs on accuracy observed in the male subjects. The differences obtained with the female group are discussed in relation to the observed modification on the negative activity around 400 msec with stimuli in the Left Hemispace. These findings give some suggestions about the interaction of structural and attentional mechanisms in the brain during the solution of a lateralized cognitive task.

Hemispheric differences in odour recognition.

Two experiments were designed in order to study hemispheric differences in odour recognition in normal subject. In the first experiment subjects first smelled an odour and then a visual stimulus (a picture or a word related or unrelated to the odour) was flashed either to the left or to the right hemisphere for 150 milliseconds. Subjects had to press a key if the two stimuli (olfactory and visual) matched and another key if they did not. Reaction time analysis showed that the responses were faster when the second stimulus (either picture or word) was presented to the right hemisphere. In a second experiment the first stimulus was auditory rather than olfactory. Subjects were instructed to listen to names of odorants and then to respond to pictures or written names as in the first experiment. In this case a left hemisphere advantage emerged, presumably related to the priming of the left hemisphere by the auditorially presented verbal stimulus.

Hemispace and information control by the two cerebral hemispheres: which interaction?

Two experiments employing subjects with different experience in tactile discrimination (blind and seeing subjects) were carried out to investigate the effect of the space location of stimuli on the information processing activity of the two cerebral hemispheres. An angle discrimination task that yields a right hemisphere superiority was used. In Experiment 1, seeing subjects showed a general superiority of the left hand (right hemisphere) which was more pronounced in the left hemispace with respect to the central and the right hemispace performance. In Experiment 2, blind subjects showed a significant superiority of the left hand in the central and in the left hemispace and no difference between the two hands in the right hemispace. In both experiments hemispace differences were due only to the modification of the left hand (right hemisphere) performance. These results suggest that the hemispace control by the contralateral hemisphere interacts only with the activity of the hemisphere dominant in the information processing.

Left hemisphere superiority for visuospatial functions in left-handers.

Male and female left- and right-handers have been tested with a divided visual field technique on a visuospatial (discrimination of angle width) and on a verbal task (vowel-consonant discrimination) using either a choice or a Go-No-go manual reaction time paradigm. Right-handers showed the expected pattern of hemispheric asymmetries with an advantage of the right hemisphere in the visuospatial task and an advantage of the left hemisphere in the verbal task. Such effects were statistically reliable only in male subjects. Left-handers, on the contrary, showed a different pattern of asymmetries. In the visuospatial task there was an overall superiority of the left hemisphere, while no hemispheric asymmetry was found in the verbal task.

Visual hemispace differences reflect hemisphere asymmetries.

The relationship between the representation of the extracorporeal visual hemispace and the contralateral hemisphere has been investigated by presenting visual stimuli foveally either in the right or in the left hemispace. In a lexical decision task (Exp. 1) and a face-familiarity decision task (Exp. 2) lateral asymmetries very similar to those obtained using the divided visual field technique have been found. These results suggest that under particular circumstances the hemispace representation in the contralateral hemisphere overrides the retinal representation. Finally, it was found that in a lexical decision task performance with stimuli in the right hemispace was very similar to that with stimuli in a central position. The physiological and adaptive meaning of this phenomenon is discussed.

Hemispheric asymmetry in face perception tasks of different cognitive requirement.

Three laterality experiments using tasks of different cognitive requirement were performed in order to determine the stage at which hemispheric differences in face perception arise. All experiments employed the same set of faces and a vocal reaction time paradigm. In experiment 1, subjects were required to discriminate male from female faces and no hemispheric asymmetries were found. In experiment 2, subjects were required to decide whether or not faces were of famous or unknown people and a right hemisphere advantage was found. Finally, in experiment 3 subjects were required to verbally identify the famous faces and no hemispheric differences were found. The results suggest that a right hemisphere superiority exists for the comparison of stimulus faces with an internal representation. Contrary to expectation, face naming does not result in a selective left hemisphere involvement.