Functional hemispheric asymmetries were examined for right- or left-handed men and women. Tasks involved (a) auditory processing of verbal material, (b) processing of emotions shown on faces, (c) processing of visual categorical and coordinate spatial relations, and (d) visual processing of verbal material. Similar performance asymmetries were found for the right-handed and left-handed groups, but the average asymmetries tended to be smaller for the left-handed group. For the most part, measures of performance asymmetry obtained from the different tasks did not correlate with each other, suggesting that individual subjects cannot be simply characterized as strongly or weakly lateralized. However, ear differences obtained in Task 1 did correlate significantly with certain visual field differences obtained in Task 4, suggesting that both tasks are sensitive to hemispheric asymmetry in similar phonetic or language-related processes.

In each of two experiments, subjects were required to identify consonant-vowel-consonant nonsense syllables projected to the left visual fiel/right hemisphere (LVF/RH), right visual field/left hemisphere (RVF/LH), or to the CENTER of the visual field. There were fewer errors on RVF/LH than on LVF/RH trials and the pattern of errors was qualitatively different on RVF/LH and LVF/RH trials. The pattern of errors was consistent with the hypothesis that attention is distributed across the three letters in a relatively slow serial fashion on LVF/RH trials whereas attention is distributed more rapidly and evenly across the three letters on RVF/LH trials. Despite the large RVF/LH advantage, the qualitative pattern of errors on CENTER trials (when viewing conditions do not favor one hemisphere or the other) was very similar to the pattern obtained on LW/RH trials. Implications of this counterintuitive finding are considered for the nature of interhemispheric interaction.

Observers identified consonant-vowel-consonant (CVC) nonsense syllables with the letters arranged horizontally. In each of 2 experiments, there were fewer errors when stimuli were presented to the right visual field (RVF) and left hemisphere (LH) than when stimuli were presented to the left visual field (LVF) and right hemisphere (RH) T and the extent to which the number of last-letter errors exceeded the number of first-letter errors was greater on LVF/RH than on RVF/LH trials. When the same stimulus was presented simultaneously to both visual fields (Experiment 2), the qualitative error pattern was very similar to the pattern obtained on LVF/RH trials. These effects replicate results obtained in earlier CVC identification experiments with letters arranged vertically. However, when a single stimulus was presented in the center of the visual field (Experiment 1), so that the first letter of the CVC projected to the LVF/RH and the last letter projected to the RVF/LH, the error pattern was a mixture of the LVF/RH and RVF/LH patterns, as if each hemisphere took the lead for processing the letter it received directly.

The present experiment examined the effects of dioptric blurring on the performance of two different spatial processing tasks using the same visual stimuli. One task (the above/below, categorical task) required subjects to indicate whether a dot was above or below a horizontal line. The other task (the coordinate, near/far task) required subjects to indicate whether the dot was within 3 mm of the line. For both tasks, the stimuli on each trial were presented to either the right visual field and left hemisphere (RVF/LH) or the left Visual field and right hemisphere (LVF/RH). For the above/below task, dioptric blurring consistently increased reaction time (RT) and did so equally on LVF/RH and RVF/LH trials. Furthermore, there was no significant difference between the two visual fields for either clear or blurred stimuli. For the near/far task, dioptric blurring had no consistent effect on either RT or error rate for either visual field. On an initial block of trials, however, there were significantly fewer errors on LVF/RH than on RVF/LH trials, with the LVF/RH advantage being independent of whether the stimuli were clear or blurred. This initial LVF/RH advantage disappeared quickly with practice, regardless of whether the stimuli were clear or blurred. This pattern of results suggests that for both cerebral hemispheres, somewhat different aspects of visual information are relevant for categorical versus coordinate spatial processing and that the right hemisphere is superior to the left for coordinate (but not categorical) spatial processing.

Previous research has indicated a relationship between reading ability and the integrity of certain phonological processing skills--skills that operate on the sound structure of language. This study shows how the deficient phonological processing skills of poor beginning readers can impair their comprehension of spoken phrases and sentences that are disambiguated by prosodic cues (i.e., pitch, stress, and pause). Following a brief summary of the available research literature, two new experiments are reported to illustrate that poor readers do not interpret certain sentences as accurately as good readers do, because they are less able to hold phonological material temporarily in working memory. Further insight into the basis of these differences between good and poor readers is provided by two additional pieces of evidence: The differences between good and poor readers are analogous to those between older and younger children readers, and the performance of poor readers tends to resemble that of younger children reading at their same level (i.e., reading-ability-matched controls). Apparently, good and poor readers tend to differ in the rate at which they develop phonological processing skills.