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1334Reaction time (RT) is known to decrease as a function of stimulus intensity, approaching an asymptote for the most intense stimuli. This is particularly true for simple reactions, but not always for more complex tasks (see, e.g., van der Molen & Keuss, 1979). Stimulus intensity has usually been considered a factor influencing only very early stages of information processing. Evidence supporting this view has come both from studies employing the additive factors method (AFM) and from psychophysiological measures. It has been shown that the intensity effect on RT is additive with the effects of other factors, such as foreperiod duration, stimulus-response compatibility, number of alternatives, stimulus probability, and practice (e.g., Everett, Hochhaus, & Brown, 1985;Niemi, 1979;Raab, Fehrer, & Hershenson, 1961;Sanders & Andriessen, 1978;Schweickert, Dahn, & McGuigan, 1988; Shwartz, Pomerantz, & Egeth, 197). According to AFM, the additivity of intensity and other factors means that the stage affected by intensity is different from the stages affected by those other factors. Therefore, one might reasonably assume that this particular stage occurs very early in processing, distant from other stages. This claim has gained further support from electrophysiological studies in which the effect of intensity on simple RT and on the latency of early components of event-related potentials (ERPs) have been directly compared. Using this approach, Vaughan, Costa, and Gilden (1966), Wilson and Lit (1981), and Ja kowski, Pruszewicz, and widzi ski (1990) found that visual intensity had identical effects on simple RT and on the latency of the N1 component. These findings suggested that the processes later than those reflected by the N1 (which peaks at about 100-150 msec) are independent of stimulus intensity. Evidence from a number of other studies, however, is in conflict with this view. Locus of the intensity effect in simple reaction time tasks ROLF VERLEGER University of Lübeck, Lübeck, GermanyEvidence is still inconclusive regarding the locus of the stimulus intensity effect on information processing in reaction tasks. Miller, Ulrich, and Rinkenauer (1999) addressed this question by assessing the intensity effect on stimulus-and response-locked lateralized readiness potentials (LRPs) as indices of the sensory and motor parts of reaction time (RT). In the case of visual stimuli, they observed that application of brighter stimuli resulted in a shortening of RT and stimulus-locked LRP (S-LRP), but not of response-locked LRP (R-LRP). The results for auditory stimuli, however, were unclear. In spite of a clear RT reduction due to increased loudness, neither S-LRP nor R-LRP onset was affected. A reason for this failure might have been a relatively small range of intensity variation and the type of task. To check for this possibility, we performed three experiments in which broader ranges of stimulus intensities and simple, rather than choice, response tasks were used. Although the intensity effect on the R-LRP was negligible, ...

health psychology report • volume 8(1),  original article background The impact of bilingualism on lateralized brain functions such as praxis -the control of skilled actions -and language representations themselves, particularly in the auditory domain, is still largely unknown. Recent studies suggest that bilingualism affects both basic (fundamental frequency) sound and action-related speech processing. Whether it can impact non-verbal action sound processing is a question of debate. participants and procedureHere we examined twenty bilinguals using a dichotic listening paradigm, in which in addition to repeating the just heard action words, participants named -in Polish or English -one of two simultaneously presented tool sounds from attended ears. The results were compared with data from these same participants tested with reading the same words in a visual-half field paradigm. resultsIn contrast to typical outcomes from monolinguals, the laterality indices of action-related sound processing (verbal and non-verbal) were not left lateralized but hemispherically balanced. Notably, despite similar organization of tool-and action-word sound processing, their auditory (balanced) and visual-language (left-lateralized) representations might be independent because there were no significant correlations between any of their laterality indices. conclusionsThis indicates that bilingualism might involve reshuffling/ reorganization of typically lateralized brain functions and such plasticity will have consequences for second language learning strategies, as well as for neurorehabilitation.