Constraints have different concurrent effects and aftereffects on variability

Three experiments showed that constraints imposed early in learning have different effects on variability when they are in effect and after they are removed. Task constraints, which determine how something can be done, limited the number of possible responses in a computer game. Variability constraints, which specify how differently something must be done, required that each response differ from some number of prior responses. Less restrictive constraints (Experiments 1 and 2) produced higher variability during the constraints. More restrictive constraints (Experiments 2 and 3) led to higher variability after the constraints were relaxed. The authors discuss how these differences reflect strategies acquired during the constraints (default rules) and modified in closely related ways (exception rules) afterward.     

Personally familiar proper names are relatively successfully processed in the human right hemisphere; or, the missing link

Responding to our abstract in Brain and Language (Ohnesorge & Van Lancker, 1999), which proposed that famous proper nouns are successfully processed in both cerebral hemispheres, Schweinberger, Landgrebe, Mohr, and Kaufmann (2001) claimed that the "link" between personal names and the right hemisphere is "illusory." Ohnesorge and Van Lancker (2001) further described six experimental studies in which LVF/RH recognition of famous proper nouns was influenced by task conditions and stimulus familiarity. Here presenting two more experiments performed to explore the refutation presented by Schweinberger et al., this article confirms an ability of the right hemisphere to recognize famous proper nouns and explains why appropriate stimulus development and task conditions are essential in furthering our understanding of the role of the right hemisphere in processing personal relevance.     

Effect of speech task on intelligibility in dysarthria: a case study of Parkinson's disease

This study assessed intelligibility in a dysarthric patient with Parkinson's disease (PD) across five speech production tasks: spontaneous speech, repetition, reading, repeated singing, and spontaneous singing, using the same phrases for all but spontaneous singing. The results show that this speaker was significantly less intelligible when speaking spontaneously than in the other tasks. Acoustic analysis suggested that relative intensity and word duration were not independently linked to intelligibility, but dysfluencies (from perceptual analysis) and articulatory/resonance patterns (from acoustic records) were related to intelligibility in predictable ways. These data indicate that speech production task may be an important variable to consider during the evaluation of dysarthria. As speech production efficiency was found to vary with task in a patient with Parkinson's disease, these results can be related to recent models of basal ganglia function in motor performance.     

Variability in aphasic patients' response times

Response time studies of acquired language disorders are plagued by tremendous variability in patients' response times. In this brief report we demonstrate how variability itself may provide informative data. Lexical decision response times, generated by nine patients, illustrate how within-patient variability may estimate stability in cognitive dynamics.     

The influence of word frequency on recency effects in directed free recall

Leading theoretical explanations of recency effects are designed to explain the reported absence of a word frequency effect on recall of words from recency serial positions. The present study used a directed free-recall procedure (J. J. Dalezman, 1976) and manipulated the frequency composition of the word lists (pure and mixed). Overall, with pure lists, a greater proportion of high-frequency (HF) words were recalled than low-frequency (LF) words, and with mixed lists, a greater proportion of LF words were recalled than HF words. Of importance, this recall advantage for one frequency over the other as a function of list composition was evident across the last three serial positions, indicating an influence of word frequency on recency effects that is dependent on the frequency composition of the lists. These results challenge one of the major assumptions on which several theories of recency effects have been based.     

Lateralization of narrow-band noise by blind and sighted listeners

The effects of varying interaural time delay (ITD) and interaural intensity difference (IID) were measured in normal-hearing sighted and congenitally blind subjects as a function of eleven frequencies and at sound pressure levels of 70 and 90 dB, and at a sensation level of 25 dB (sensation level refers to the pressure level of the sound above its threshold for the individual subject). Using an 'acoustic' pointing paradigm, the subject varied the IID of a 500 Hz narrow-band (100 Hz) noise (the 'pointer') to coincide with the apparent lateral position of a 'target' ITD stimulus. ITDs of 0, +/-200, and +/-400 micros were obtained through total waveform delays of narrow-band noise, including envelope and fine structure. For both groups, the results of this experiment confirm the traditional view of binaural hearing for like stimuli: non-zero ITDs produce little perceived lateral displacement away from 0 IID at frequencies above 1250 Hz. To the extent that greater magnitude of lateralization for a given ITD, presentation level, and center frequency can be equated with superior localization abilities, blind listeners appear at least comparable and even somewhat better than sighted subjects, especially when attending to signals in the periphery. The present findings suggest that blind listeners are fully able to utilize the cues for spatial hearing, and that vision is not a mandatory prerequisite for the calibration of human spatial hearing.     

Change in cognitive functioning associated with apoE genotype in a community sample of older adults

The influence of a genetic risk factor, apolipoprotein E (apoE) epsilon4 variant, was assessed in older adults aged 70 to 94 on 3 occasions over 7 years. The results of latent growth curve analyses are reported for individuals genotyped for apoE at the 2nd measurement occasion (n = 601) and for a subsample of individuals without probable or definite dementia during the 1st or 2nd occasion (n = 434). ApoE-epsilon4 status was a significant predictor of level and change in memory performance and change in speed performance in the full sample, and of initial level and change in memory performance in the nondemented subsample. These results support previous findings that apoE-epsilon4 is associated with accelerated memory deterioration in individuals without clinical dementia.     

Employment of persons with disabilities in information technology jobs: literature review for "IT works"

This article reviews relevant literature as to the labor pool of qualified individuals with disabilities and employment in information technology (IT) sector jobs. First, the article reviews the empirical literature on barriers to employment in IT for persons with disabilities. The examination then is extended to studies of barriers to employment for individuals with disabilities in other employment sectors. Findings illustrate the limited experiences that IT and non-IT companies have in employing and accommodating employees with disabilities. Implications are discussed for enhancing the employment of qualified workers with disabilities in IT through research, education, training, and mentoring programs.