A fast procedure for studying conditional accuracy functions

This paper describes a procedure for obtaining conditional accuracy functions(CAFs) from naive observers and a restricted number of trials. The method permits the experimenter to counter the subjects’ tendency to favor accuracy in tasks in which stimulus discrimination is easy. Each time a block of 12 trials contains less than three errors, observers are instructed, by means of a speed-up signal, to respond faster. The subject is continuously informed about her/his effective reaction time. The data show that the desired speed-accuracy tradeoff was obtained within each of the 7 observers. The mean percent error was around 25%.     

Feature processing during high-rate auditory selective attention

Auditory event-related brain potentials (ERPs) and reaction times were, analyzed in a selective attention task in which subjects attended to tone pips presented at high rates-Xinterstimulua intervals [ISIs] of 40-200 msec). Subjects responded to infrequent target tones of a specified frequency (250 or 4000 Hz) and location (left or right ear) that were louder than otherwise identical tones presented randomly to the left and right ears. Negative difference (Nd) waves were isolated by subtracting ERPs to tones with no target features from ERPs to the same tones when they shared target location, frequency, or both frequency and location cues. Nd waves began 60-70 msec after tone onset and lasted until 252–350 msec after tone onset, even for tones with single attended cues. The duration of Nd waves exceeded the ISIs between successive tones, implying that several stimuli underwent concurrent analysis. Nd waves associated with frequency processing had scalp distributions different from those associated with location processing, implying that the features were analyzed in distinct cortical areas. Nd waves specific to auditory feature conjunction were isolated. These began at latencies of 110–120 msec, some 30-40 msec after the Nds to single features. The relative timing of the different Nd waves suggests that auditory feaure conjunction begins after a brief parallel analysis of individual features but before feature analysis is complete.     

Responding to allegations of scientific misconduct

Institutions in France are not yet well prepared to respond to allegations of scientific misconduct. Following a serious allegation in late 1997. INSERM,* the primary organization for medical and health-related research in France, began to reflect on this subject, aided by scientists and jurists. The conclusions have resulted in establishing a procedure to be followed in cases of alleged misconduct, and also in reinforcing the application of good laboratory practices within each laboratory. Guidelines for authorship practices and scientific assessment must also be considered. Even though each institution must remain responsible for responding to allegations of scientific misconduct within its doors, INSERM would like to see national, European, and international co-ordination about the methods of such response. Institut National de la Santé et de la Recherche Médicale (eng. French National Medical Research Institute) is known as INSERM. An earlier version of this paper was presented at a symposium, Scientific Misconduct: An International Perspective, organised by The Medical University of Warsaw, 16 November, 1998.     

The “Poffenberger” and “Dimond” Paradigms: Interrelated Approaches to the Study of Interhemispheric Dynamics?

Brown and Jeeves (1993) found that an evoked potential estimate of interhemispheric transfer time, from the left to the right hemisphere, correlated negatively with a bilateral field advantage (BFA) in a response-choice letter matching task. We implemented a go no-go dot size matching task to determine whether the crossed-uncrossed difference (CUD) in reaction time, commission errors and omission errors (estimates of the “cost” of interhemispheric transfer) would correlate with BFAs in data from the same experiment and whether the type of decision (“same” versus “different”) would modulate the CUDs and/or BFAs. Sixteen normal right-handed subjects were tested. The CUDs were negatively correlated with the BFAs. Canonical correlation analysis of this set of relations was highly significant (r= .95). Estimates of left-to-right relay were far more strongly related to BFA (p= .0001) than were estimates of right-to-left relay (p= .03). “Same” decisions yielded a unilateral field advantage and “different” decisions a bilateral field advantage in omission error data, this crossed interaction reaching significance. More efficient interhemispheric relay favored BFAs, i.e., strongly suggesting in such cases an advantage of interhemispheric over intrahemispheric integration. This effect appeared to be markedly asymmetric. Furthermore, resource sharing within and between the hemispheres was a function of the “same” versus “different” dimensions of the decision to be made, especially in omission errors. The opposite dissociation occurred less markedly in the reaction times, this double dissociation reaching significance, revealing presence of a subtle speed–accuracy trade-off in interhemispheric dynamics.     

Reaction times as a measure of uncertainty

In this article, a method is presented to analyse relationships between detection or discrimination frequencies and reaction times in psychophysical tasks. It is shown in three empirical data sets that reaction time decreases as a linear function of the absolute value of the logit transforms of the response probabilities. Such a function stresses the characteristic uncertainty associated with subjects' responses and the relation between their response parameters and the response criterion used by the subjects.     

A choice reaction time index of callosal anatomical homotopy

Tachistoscopically presented bilateral stimulus pairs not parallel to the meridian produced significantly longer RTs on a task requiring discrimination of shapes (Go/no-Go) than pairs emplaced symmetrically on each side of the meridian in Desjardins and Braun [Desjardins, S., & Braun, C. M. J. (2006). Homotopy and heterotopy and the bilateral field advantage in the Dimond paradigm. Acta Psychologica, 121,  125–136]. This was explained by the fact that there are more homotopic than heterotopic fibers in the corpus callosum. However: (1) different parts of the visual field were not equiprobably stimulated, possibly causing subtle biases, (2) the predicted cost of vertical asymmetry was tested only with bilateral stimuli, and (3) interstimulus distance was at the outer limit of callosal midline fusion (10.6°). Here, a tachistoscopic experiment with 24 normal participants replicated the between-field vertical symmetry advantage [Desjardins, S., & Braun, C. M. J. (2006). Homotopy and heterotopy and the bilateral field advantage in the Dimond paradigm. Acta Psychologica, 121, 125–136.], but without irrelevant stimulation conditions and with more proximal stimuli. In addition, a significant specific cost of vertical asymmetry of 7 ms was found for between-field integration over within-field integration. As far as we know, this is the first demonstration of an effect of callosal anatomical homotopy with reaction time.     

Stereotype threat and inflexible perseverance in problem solving

The present research examines whether women burdened by stereotype threat, a threat of confirming negative ingroup stereotypes (Steele, C. M., & Aronson, J. (1995). Stereotype threat and the intellectual test performance of African Americans. Journal of Personality and Social Psychology, 69(5), 797-811), are less able to abandon old strategies and employ newer, more efficient ones when conditions change. In two studies, stereotype threat was found to increase inflexible perseverance: women made to believe they were taking a diagnostic math/spatial ability test, compared to those not threatened by stereotypes, were more likely to use previously successful but presently inefficient or incorrect strategies. In Study 1, participants under stereotype threat also suppressed relevant stereotypes to the greatest degree, and their inflexible perseverance was predicted by the degree to which they suppressed these stereotypes. Implications for test performance and potential decision-making effects of stereotype threat are discussed.