The accuracy of memory for faces of personally known individuals

The present study was aimed at evaluating whether the very high accuracy of memory for familiar faces, demonstrated by Ge et al (2003, Perception 32 601-614) with a very familiar famous person, generalises to faces of personally known individuals. The accuracy of participants' perceptual memory for a close colleague's face and for their own face was evaluated by presenting original and manipulated pictures of these two targets. The manipulation consisted of increasing or decreasing the interocular distance. As in Ge et al's study, results indicated that proportions of correct recognition of the original faces, and just noticeable differences for the detection of alterations in the recognition task, were not significantly different from the corresponding measures in a perceptual discrimination task performed by a sample of participants who did not know the target persons at all. High accuracy of memory generalises to faces of personally known individuals.     

Les techniques biomédicales en matière d’assistance médicale à la procréation conçues dans l’objectif de pallier l’infertilité médicale peuvent-elles évoluer de manière à être utilisées pour remédier à l’infertilité sociale ?

Medically assisted procreation includes techniques that may allow infertile couples to procreate. However, the application of 2011 bioethics law reveals lots of paradox and high-risk behaviors which arouse the question of the relevance and advisable aspect of its opening to all women.     

Time-course of hemispheric preference for processing contralateral relevant shapes: P1pc, N1pc, N2pc, N3pc

A most sensitive and specific electrophysiological indicator of selective processing of visual stimuli is the N2pc component. N2pc is a negative EEG potential peaking 250 ms after stimulus onset, recorded from posterior sites contralateral to relevant stimuli. Additional deflections preceding or following N2pc have been obtained in previous studies, possibly produced by specific stimulus features or specific prime-target sequences. To clarify the entire time-course of the contralateral- ipsilateral (C-I) difference recorded from the scalp above visual cortex in response to left-right pairs of targets and distracters, C-I differences were here compared between two types of stimuli and between stimuli that were or were not preceded by masked neutral primes. The C-I difference waveform consisted of several peaks, termed here P1pc (60-100 ms after target onset), N1pc (120-160 ms), N2pc (220-280 ms), and N3pc (360-400 ms). Being markedly enhanced when stimuli were preceded by the neutral primes, P1pc may indicate a response to stimulus change. Also, when stimuli were primed, N2pc reached its peak earlier, thereby tending to merge with N1pc. N3pc seemed to increase when target discrimination was difficult. N1pc, N2pc, and N3pc appear as three periods of one process. N3pc probably corresponds to L400 or SPCN as described in other studies. These observations suggest that the neurophysiological basis of stimulus-driven focusing of attention on target stimuli is a process that lasts for hundreds of milliseconds, with the relevant hemisphere being activated in an oscillating manner as long as required by the task.     

VEP latency and some properties of simple motor reaction-time distribution

Summary The median of simple motor reaction (RT) to a flash parallels the latencies of visually evoked potential (VEP) deflections if flash intensity is varied. However, mean and median reaction times are not equal because of the skewness of RT distribution. It therefore seemed plausible that the mean reaction time — intensity relationship would be steeper than that for VEP latency. Such divergence would account for the intensity-dependent motor component of RT revealed by other psychophysical studies. The latencies of VEP deflections were measured as a function of intensity and the results were compared with mean and median RTs. The difference between mean and median RT is constant and independent of flash intensity. Moreover, both values are parallel to VEP latency. The general pattern of results remains the same after a change in the distribution from which the foreperiod is sampled.