As noted by Satz, the prevalence of lateralized language in the general population is underestimated substantially by the proportion of people who show the typical asymmetry on a laterality task. In a series of two dichotic listening experiments with a total of 171 right-handers and 170 left-handers, we tested the hypothesis that increased reliability of measurement will lead to increased classification accuracy. Experiment 1 showed that neither the frequency nor magnitude of the right-ear advantage (REA) for fused rhyming words increased as the number of trials increased from 120 to 480. Ear-difference scores were highly reliable (r = .85), even when based on 120 trials. Experiment 2, which involved lists of dichotic word pairs, yielded similar results. Even though retest reliability of the ear-difference score for 132 word pairs was only .45, neither the incidence nor strength of the REA increased significantly when the number of pairs was increased to 528. The results indicate that the poor classification accuracy of dichotic listening tasks cannot be attributed to unreliability. (JINS, 2000, 6, 539–547.)

Recognition memory for words and designs was assessed in epilepsy patients who underwent unilateral anterior temporal lobectomy. Memory was assessed during the intracarotid amobarbital test (IAT) performed prior to surgery and also following surgery. Memory discrimination and response bias lateralized differently. Memory discrimination, or memory accuracy, lateralized as a function of the type of material used in memory testing. Left temporal lobe lesions resulted in more impaired discrimination of verbal materials; right temporal lobe lesions resulted in more impaired discrimination of visuospatial materials. Response bias, the decision rule adopted in situations of uncertainty, was more liberal following left temporal lobe lesions for both verbal and visuospatial materials. Findings suggest that the two cerebral hemispheres are differentially specialized for encoding different types of information in long term memory, and that this impacts on decision strategies in situations of memory uncertainty. (JINS, 1998, 4, 502-511.)

The relationships of medical, developmental, social, and familial variables to intellectual performances (IQ scores) were assessed in a sample of 242 adult patients with intractable lateralized temporal lobe epilepsy. Lower IQ scores were associated with low patient and parent education. In addition to the significant contributions of nonneurological social and familial factors to IQ, early age at onset of regular seizures and presence of primary neurological dysfunction in the left cerebral hemisphere were also both independently related to lower IQ. The obtained results suggest that the occurrence of regular seizures during a critical period in early childhood neural maturation poses the greatest risk to cognitive development in the epilepsy population. Total duration of seizures, history of severe convulsive episodes, and the occurrence of another nonepileptic neurological problem in early childhood do not contribute significantly to delayed cognitive development. (JINS, 1997, 3, 252–259.)

Material-specific memory dysfunction was assessed using a nonverbal, visuospatial, supraspan learning test, the Biber Figure Learning Test-Extended (BFLT-E), in 71 left-hemisphere language-dominant epilepsy patients prior to anterior temporal lobectomy (ATL) and in 48 age-matched healthy subjects. Two matched forms of the BFLT-E yielded comparable scores, indicating that this task may be used to track memory performance over time in individual patients. Right temporal lobe epilepsy (RTLE) and left temporal lobe epilepsy (LTLE) patients performed below healthy subjects on all free-recall measures. RTLE, but not LTLE, patients also differed from healthy subjects in recognition memory discrimination. Furthermore, the RTLE patients performed below LTLE patients on measures specific to long-term memory abilities. The BFLT-E appears to be a useful clinical tool for assessing different components of visuospatial memory in patients with lateralized mesial temporal lobe (MTL) dysfunction. The test is sensitive to visuoconstructional problems associated with various types of brain damage, but it also distinguishes material-specific, nonverbal, visuospatial memory impairments in patients with neurological dysfunction in the non language-dominant right temporal lobe.