Individual Differences in Performance Speed Are Associated With a Positivity/Negativity Bias. An ERP and Behavioral Study

There is a current dispute over the origins, incidence, and development of Positivity Bias, i.e., preferential processing of positive relative to negative information. We addressed this question using a multi-method technique of behavioral, psychometric and event-related potential (ERP) measures in a lexical decision task (LDT). Twenty-four university students (11 female) participated (age range 18–26), but four were omitted owing to data issues. Participants were classified as Positivity Biased (PB) if their LDT responses to positive words were faster than negative words, and vice versa for those classified as Negativity Biased (NB), leading to a group of 11 PB participants and a group of 9 NB participants. Interestingly, the PB group was significantly faster overall than the NB group and had significantly shorter P2 component ERP latencies in the left occipital region. Furthermore, the PB group had significantly higher scores for expressive suppression (ES), together with higher scores for Crystallized Knowledge and for cognitive reappraisal (CR). These results suggest that around 55% of the students had Positivity Bias, and these were more efficient in processing information and had better emotion regulation abilities than those with a Negativity Bias

Seeing is knowing? Visual word recognition in non-dyslexic and dyslexic readers: an ERP study

The aim of the current study was to investigate whether phonological/semantic processing of the word takes place simultaneously with, or following, the early processing of its visual features. Event related potentials (ERPs) were recorded in 13 dyslexic (four female) and 14 non-dyslexic (six female) native English speaking young adults in two lexical decision tasks. In Task 1 participants had to make an orthographic lexical decision to distinguish frequently used words (W) from pseudohomophones (PH1)focusing on visual properties of stimuli. In Task 2 they had to make a phonological lexical decision—to pseudohomophones (PH2) and pseudowords (PW) and decide whether stimuli sounded like real words—focusing on non-visual higher order, i.e., phonological and semantic, processing of the stimuli. The behavioural performance was less good and the ERP peaks’ latency longer in dyslexics compared to controls. The reaction times (RTs) and the number of errors (reversed for the controls in Task 2) increased across four conditions for both groups in the following order: W< PH1< PH2< PW. The ERPs were larger in Task 2 compared to Task 1 starting at 100 ms (P1) for the controls and from about 220 ms (P2) for the dyslexics. The latency of N2 peak in left occipito-temporal sites was larger (as was the number of errors) in PH2 compared to PW condition in controls only, which indicates phonological/semantic specific processing at a time latency of 250–260 ms. Thus, the visual task required less effort than the phonological task, dyslexics’ behavioural performance was less good and the brain activation delayed compared to controls. Combined behavioural and ERP results of this study indicated that phonological/semantic processing of the word took place 150 ms after processing of its visual features in controls and possibly later in dyslexics

Nicotine enhances an auditory Event-Related Potential component which is inversely related to habituation

Nicotine is a psychoactive substance that is commonly consumed in the context of music. However, the reason why music and nicotine are coconsumed is uncertain. One possibility is that nicotine affects cognitive processes relevant to aspects of music appreciation in a beneficial way. Here we investigated this possibility using Event-Related Potentials (ERPs). Participants underwent a simple decision-making task (to maintain attentional focus), responses to which were signaled by auditory stimuli. Unlike most previous research looking at the effects of nicotine on auditory processing, we used tones of different pitch, a fundamental element of music. In addition, unlike most other studies, we tested non-smoking subjects to avoid withdrawal-related complications. We found that nicotine (4.0 mg, administered as gum) increased P2 amplitude in the frontal region. Since a decrease in P2 amplitude and latency is related to habituation processes, and an enhanced ability to disengage from irrelevant stimuli, our findings suggest that nicotine may cause a reduction in habituation, resulting in non-smokers being less able to adapt to repeated stimuli. A corollary of that decrease in adaptation may be that nicotine extends the temporal window during which a listener is able and willing to engage with a piece of music

Reading words and pseudowords in dyslexia: ERP and behavioural tests in English-speaking adolescents

The study reports neurophysiological and behavioural correlates of lexical decision processes in English speaking dyslexic and non-dyslexic readers. Nine dyslexic adolescents (ages 15.6–17.8) and 9 control (ages 15.4–19.3) adolescents were tested, and the event related potentials (ERPs) to words and pseudowords were recorded simultaneously with behavioural measures. As expected, both groups showed significantly lower accuracy and longer response times for the pseudowords. Furthermore, overall performance (in terms of lower accuracy and longer response times) was significantly worse for the dyslexic group. The ERP analysis indicated that the later positive peaks, P4 (around 400 ms from stimulus onset) and P5 (around 500 ms), were significantly delayed and attenuated for the dyslexic group. Analysis of the early ERP peaks recorded in the occipitotemporal region led to an interesting dissociation. The controls showed a left lateralised Condition effect, with the amplitude of P1 significantly smaller to words than pseudowords. By contrast, there was no such lexical effect for the dyslexic group, with equal P1 amplitudes for words and pseudowords, at the control level for pseudowords. The deviations in the early ERP components of dyslexics support the evidence of deficits in pre-lexical visual word form recognition within the first 110 ms of activation together with altered hemispheric asymmetry. In addition, the slowed and attenuated late ERP components and weaker behavioural performance of the dyslexic group highlight deficits in the later, cognitive, processing stages

The accuracy of metric judgements : perception of surface normal

Observers adjusted a probe (a short rod) to appear normal to a planar surface slanted in depth. In Experiment 1, observers (N = 12) performed this metric task in two conditions: with reduced cues to calibration of binocular viewing parameters and with full cues. The results provided evidence for the use of an internal working metric in metric tasks because they confirm predictions that (i) errors should be largely systematic and accounted for by assuming an inaccurate working metric and (ii) this metric should be consistent with miscalibration of relevant viewing parameters. The data support the prediction that performance errors decrease in a manner consistent with improved binocular calibration, when better cues to relevant viewing parameters are provided. We performed two additional control experiments as further tests of the binocular miscalibration account, to determine whether performance in Experiment 1 could be explained instead by the use of monocular cues. We found that monocular performance was significantly poorer than binocular performance in reduced-cue conditions (Experiment 2) and full-cue conditions (Experiment 3). These control experiments provide confirmation that binocular cues contribute to performance in the full-cue conditions of Experiment 1, and that disparity was the only effective cue to slant in reduced-cue conditions