Gabriel Besson

Fast and Famous: Looking for the Fastest Speed at Which a Face Can be Recognized

Face recognition is supposed to be fast. However, the actual speed at which faces can be recognized remains unknown. To address this issue, we report two experiments run with speed constraints. In both experiments, famous faces had to be recognized among unknown ones using a large set of stimuli to prevent pre-activation of features which would speed up recognition. In the first experiment (31 participants), recognition of famous faces was investigated using a rapid go/no-go task. In the second experiment, 101 participants performed a highly time constrained recognition task using the Speed and Accuracy Boosting procedure. Results indicate that the fastest speed at which a face can be recognized is around 360–390 ms. Such latencies are about 100 ms longer than the latencies recorded in similar tasks in which subjects have to detect faces among other stimuli. We discuss which model of activation of the visual ventral stream could account for such latencies. These latencies are not consistent with a purely feed-forward pass of activity throughout the visual ventral stream. An alternative is that face recognition relies on the core network underlying face processing identified in fMRI studies (OFA, FFA, and pSTS) and reentrant loops to refine face representation. However, the model of activation favored is that of an activation of the whole visual ventral stream up to anterior areas, such as the perirhinal cortex, combined with parallel and feed-back processes. Further studies are needed to assess which of these three models of activation can best account for face recognition.

Bridging novelty and familiarity-based recognition memory: A matter of timing

ABSTRACT Novelty detection is essential to adapt to changes. However, the relationship between novelty detection and visual recognition memory remains unclear. To characterize the temporal dynamics of novelty and its connection to familiarity, we probed early behavioural performance of novelty and familiarity in 31 participants using a speeded go/no-go recognition task with a 600-ms response deadline. Responses to familiarity and novelty produced symmetrical biases and correlated accuracies and biases, but novelty decisions were less accurate and had slower minimal reaction times (410 ms). These processes thus appear to be independent, as suggested by a more efficient system in the case of familiarity, but with common factors bringing overlapping contributions to both processes. This may possibly be explained by the more fluent processing of repeated stimuli, but with familiarity and novelty potentially relying on one decision criterion, as suggested by the correlated and remarkably symmetrical biases. This study supports models that conceptualize novelty and familiarity decisions as two partly overlapping processes.

Testing a New Memory Task Sensitive to Early Entorhinal/Perirhinal Atrophy in Alzheimer's disease

Background:To describe cognitive decline, a large variety of neuropsychological tests are available. Linguistic processing is an important factor in some of these tests because language disturbances might serve as a strong indicator for an underlying neurodegenerative disorder, such as Alzheimer’s disease. However, the current instruments for language assessment mainly focus on product measures, ignoring the importance of the process that leads to written or spoken language production. In this study, we aim to describe and test writing differences between healthy and cognitively impaired elderly on the basis of a selection of product and process variables. The latter are mainly related to pause times, because the number, length and location of pauses characterize writing fluency and flow. As a consequence, they are proven to reveal traces of the complexity of underlying cognitive processes. Methods: We matched fifteen cognitively impaired patients (10 patients with mild cognitive impairment and 5 patients with probable Alzheimer’s disease) with fifteen cognitively healthy elderly for gender and age. Our research involved two copy and two picture description tasks. Both tasks were logged with Inputlog, a keystroke logging tool that allowed us to log and time stamp keystroke activity to reconstruct and describe text production processes. Results:Preliminary analysis showed some promising results for cognitive effort related to word production in a written task. We used mixed effects models that included participants as a random effect and word categories as a fixed effect. Our presentation will focus on both product and process measures. Results associated with the process leading to a final text will mainly focus on pause times. For instance, cognitively impaired patients pause longer than healthy controls before, within and after words. Conclusions:Neuropsychological tests that assess language production based on patients’ writing processes could be used for assessing cognitive decline in the future. As will be illustrated in our presentation, analyses already revealed a number of key variables that could distinguish cognitively impaired from healthy elderly. Hence, this points to a set of predefined and strictly controlled product and process aspects as important criteria for improving the current task design.

Impaired familiarity in individuals at risk for Alzheimer's disease: Commentary on Schoemaker et al. (2016)

Interventions aiming at postponing or preventing the development of Alzheimer’s dementia (AD) should be implemented before the first clinical symptoms. It is therefore critical to identify individuals with incipient AD. The most inexpensive and noninvasive way to achieve this goal is the use of cognitive tests that are sensitive to initial AD cerebral pathology. More specifically, the earliest cognitive deficit should be one that affects the specific function that is supported by the entorhinal and perirhinal cortices where neurofibrillary tangles start to accumulate [1]. Recent advances in cognitive neuroscience indicate that the entorhinal and perirhinal areas play a critical role in familiarity-based memory [2], the feeling that some information has been encountered before. This function contrasts with recollection, in which one recalls qualitative details about the encounter with the information. Although compelling and theoretically founded, the hypothesis that impaired familiarity may be a very early cognitive marker of AD has not been much investigated and led to inconsistent findings for reviews [3,4]. Recently, Schoemaker, Poirier, Escobar, Gauthier, and Pruessner (2016, Alzheimer’s and Dementia: Diagnosis, Assessment and Disease Monitoring, 2, 132–139) addressed this hypothesis by testing cognitively healthy individuals who carry or not the ε4 allele of the APOE gene [5]. In this study, 21 carriers of APOE ε4 (at risk for AD) and 60 noncarriers performed a memory task in which they studied pictures of faces under two conditions that differed in terms of the spatial location of the face, the color of the background, and the judgment to make about each face. Then, participants had to recognize the faces studied under the two conditions among new faces. For each face, they had to indicate whether the face had been presented, and if so, in which condition. In this task, recollection was indexed by the proportion of targets that were correctly identified as old and that were also attributed to the correct encoding condition. In contrast, familiarity was measured by the proportion of targets that