The eye contact effect on naming famous faces

Tese de mestrado, Neurociências, Faculdade de Medicina, Universidade de Lisboa, 2012A perceção de contacto ocular tem um efeito modulador em vários aspetos do processamento cognitivo, podendo facilitar o reconhecimento facial ou o acesso à memória semântica. Nesse sentido, realizaram-se duas experiências para analisar o efeito do contacto ocular na capacidade de nomeação de faces famosas e a sua variação dependentemente do tipo de tarefa. Na primeira experiência foi apresentado um conjunto de faces famosas masculinas a um grupo de participantes, com mais de 50 anos de idade, sem doença neurológica conhecida.. As faces foram apresentadas aleatoriamente em contacto ocular ou em olhar desviado e foi pedido aos participantes para realizarem uma tarefa de nomeação das faces. Numa segunda tarefa de controlo foi solicitado aos participantes para indicarem a presença ou ausência de contacto ocular, nos estímulos apresentados. Na segunda experiência, repetiram-se as tarefas de nomeação e identificação da direção do olhar, tendo sido acrescentadas um igual número de faces femininas aos estímulos e adicionada uma tarefa de descriminação de género. Em ambas as experiências foi encontrado um efeito facilitador do contacto ocular na nomeação das faces que pertenciam ao mesmo género do participante. Pelo contrário, na tarefa de direção do olhar (na segunda experiência) verificou-se um efeito facilitador do contacto ocular, mas apenas para faces do género oposto ao participante. Na tarefa de género, o contacto ocular conduziu a uma redução no número de acertos para faces do género oposto. Estes resultados mostram um efeito facilitador do contacto ocular na nomeação, e a sua dependência de fatores como o género. A existência de um efeito facilitador do contacto ocular está então, dependente do tipo de tarefa (nomeação, género e descriminação da direção do olhar) e da interação entre a tarefa e o género observador/estímulo. Assim o efeito modulador do contacto ocular, nas diferentes atividades cognitivas é complexo, podendo facilitar ou interferir dependendo da tarefa e da sua interação com outras variáveis. O efeito facilitador, a confirmar em situações patológicas, poderá ser utilizado na reabilitação das dificuldades de nomeação.Awareness of eye contact has a modulatory effect on several cognitive tasks, enhancing facial recognition and encoding, as well as the access to semantic memory related to these faces. To analyse the effect of eye contact on proper name retrieval, and how it may depend upon type of task, two experiments using famous faces as stimuli were designed. In the first experiment a set of well-known public male faces was presented randomly in eye contact or averted gaze. Participants were asked to perform two tasks, one in which they had to name the presented faces and a control task in which they had to discriminate gaze direction. Since in this experiment all stimuli were male, a second experiment added an equal number of female and male faces. In this experiment a gender decision task was added. Participants were adult volunteers with fifty or more years, without known mental or neurological disease. Results from both experiments showed a facilitator effect of eye contact in naming faces of the same sex as the participant. In the gaze direction task of the second experiment, eye contact was easier to discriminate compared to averted gaze but only when the presented face was of the opposite sex than the participant’s. In the gender task, eye contact diminished accuracy but only with opposite-sex faces. These results show that eye contact facilitates proper name retrieval, but that this effect depends upon the sex of the perceiver and the perceived face. The existence of a facilitation effect due to eye contact was shown to be dependent both of task and of the interaction of sex of the stimuli and the participant. The modulator effect of eye contact in different cognitive tasks seems to be complex, either being a facilitator or causing interference depending on type of task and its interaction with other variables. Its facilitator effect, if confirmed in cases of pathology, may be used in rehabilitation settings of proper name retrieval

Orientation effects support specialist processing of upright unfamiliar faces in children and adults

It is considerably harder to generalize identity across different pictures of unfamiliar faces, compared with familiar faces. This finding hints strongly at qualitatively distinct processing of unfamiliar face stimuli—for which we have less expertise. Yet, the extent to which face selective versus generic visual processes drive outcomes during this task has yet to be determined. To explore the relative contributions of each, we contrasted performance on a version of the popular Telling Faces Together unfamiliar face matching task, implemented in both upright and inverted orientations. Furthermore, we included different age groups (132 British children ages 6 to 11 years [69.7% White], plus 37 British White adults) to investigate how participants’ experience with faces as a category influences their selective utilization of specialized processes for unfamiliar faces. Results revealed that unfamiliar face matching is highly orientation-selective. Accuracy was higher for upright compared with inverted faces from 6 years of age, which is consistent with selective utilization of specialized processes for upright versus inverted unfamiliar faces during this task. The effect of stimulus orientation did not interact significantly with age, and there was no graded increase in the magnitude of inversion effects observed across childhood. Still, a numerically larger inversion effect in adults compared to children provides a degree of support for developmental changes in these specialized face abilities with increasing age/experience. Differences in the pattern of errors across age groups are also consistent with a qualitative shift in unfamiliar face processing that occurs some time after 11 years of ag

Effects of expectation on face perception and its association with expertise

Perceptual decisions are derived from the combination of priors and sensorial input. While priors are broadly understood to reflect experience/expertise developed over one’s lifetime, the role of perceptual expertise at the individual level has seldom been directly explored. Here, we manipulate probabilistic information associated with a high and low expertise category (faces and cars respectively), while assessing individual level of expertise with each category. 67 participants learned the probabilistic association between a color cue and each target category (face/car) in a behavioural categorization task. Neural activity (EEG) was then recorded in a similar paradigm in the same participants featuring the previously learned contingencies without the explicit task. Behaviourally, perception of the higher expertise category (faces) was modulated by expectation. Specifically, we observed facilitatory and interference effects when targets were correctly or incorrectly expected, which were also associated with independently measured individual levels of face expertise. Multivariate pattern analysis of the EEG signal revealed clear effects of expectation from 100 ms post stimulus, with significant decoding of the neural response to expected vs. not stimuli, when viewing identical images. Latency of peak decoding when participants saw faces was directly associated with individual level facilitation effects in the behavioural task. The current results not only provide time sensitive evidence of expectation effects on early perception but highlight the role of higher-level expertise on forming priors

Direct gaze facilitates rapid orienting to faces: evidence from express saccades and saccadic potentials

Direct gaze is a crucial signal in human social communication, which is known to attract visual attention and modulate a wide range of behaviours. The present study investigated whether direct gaze facilitates rapid orienting to faces, which is important for adaptive on-line communication, and its neural correlates. Fifteen participants performed a rapid orienting task, in which they were instructed to saccade to peripherally presented buildings or faces containing direct or averted gaze as quickly as possible. Electroencephalographic recordings were made during the task. Shorter express saccade latencies were found for faces with direct gaze, compared to averted gaze or buildings, while no significant difference was found between faces with averted gaze and buildings. Furthermore, saccade-locked event-related potential (ERP) amplitudes in parieto-occipital areas discriminated faces with direct gaze from buildings and faces with averted gaze corroborating behavioural results. These results show that detection of direct gaze facilitates rapid orienting to faces

To read or not to read : a neurophysiological study

© 2015 Taylor & FrancisPure alexia (PA) has been associated with visual deficits or a failure to activate the visual word form area (VWFA). We report a patient with pure alexia due to posterior cortical atrophy, in whom event-related potentials revealed a delay in the P100 component and an absent N170 compared with controls. Furthermore, there was a tendency for a larger delay in P100 latencies associated with incorrectly read words. This suggests that some cases of PA might result from deficits in visual perception, signaled by the P100 early potential which could lead to an inability to consistently activate the VWFA, marked by the absent N170.This study was supported by a grant from Fundação para a Ciência e Tecnologia Portugal. RAPS. Reading Analysis with neuroPhysiological Signs, FCT. Coordinator: N. Guimarães.PTDC/EIA-EIA/113660/2009info:eu-repo/semantics/publishedVersio

Rickettsia bellii

Made available in DSpace on 2015-05-04T17:07:33Z (GMT). No. of bitstreams: 2 license.txt: 1914 bytes, checksum: 7d48279ffeed55da8dfe2f8e81f3b81f (MD5) livia_lopesetal_IOC_2014.pdf: 945880 bytes, checksum: b8249c8aef2028ffc6f14918fdd70120 (MD5) Previous issue date: 2014Fundação Oswaldo Cruz. Laboratório de Hantaviroses e Rickettsioses. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Laboratório de Hantaviroses e Rickettsioses. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Laboratório de Hantaviroses e Rickettsioses. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Laboratório de Hantaviroses e Rickettsioses. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Laboratório de Hantaviroses e Rickettsioses. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Laboratório de Hantaviroses e Rickettsioses. Rio de Janeiro, RJ, Brasil.Fundação Nacional de Saúde (FUNASA-DSEI). Mato Grosso, Brasil.Fundação Nacional de Saúde (FUNASA-DSEI). Mato Grosso, Brasil.Fundação Nacional de Saúde (FUNASA-DSEI). Mato Grosso, Brasil.Fundação Nacional de Saúde (FUNASA-DSEI). Mato Grosso, Brasil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia e Parasitologia de Mamíferos Silvestres de Reservatórios. Rio de Janeiro, RJ, Brasil.FFundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Biologia e Parasitologia de Mamíferos Silvestres de Reservatórios. Rio de Janeiro, RJ, Brasil.Instituto Nacional de Câncer. Departamento de Genética. Programa de Genética. Rio de Janeiro, RJ, Brasil / Universidade Federal do Estado do Rio de Janeiro (UNIRIO). Rio de Janeiro, RJ, BrasilInstituto Nacional de Câncer. Departamento de Genética. Programa de Genética. Rio de Janeiro, RJ, Brasil.Fundação Oswaldo Cruz. Laboratório de Hantaviroses e Rickettsioses. Rio de Janeiro, RJ, Brasil / Universidade Federal do Estado do Rio de Janeiro (UNIRIO). Rio de Janeiro, RJ, Brasil.Background: The purpose of this study was to identify the presence of rickettsia and hantavirus in wild rodents and arthropods in response to an outbreak of acute unidentified febrile illness among Indians in the Halataikwa Indian Reserve, northwest of the Mato Grosso state, in the Brazilian Amazon. Where previously surveillance data showed serologic evidence of rickettsia and hantavirus human infection. Methods: The arthropods were collected from the healthy Indian population and by flagging vegetation in grassland or woodland along the peridomestic environment of the Indian reserve. Wild rodents were live-trapped in an area bordering the reserve limits, due the impossibility of capturing wild animals in the Indian reserve. The wild rodents were identified based on external and cranial morphology and karyotype. DNA was extracted from spleen or liver samples of rodents and from invertebrate (tick and louse) pools, and the molecular characterization of the rickettsia was through PCR and DNA sequencing of fragments of two rickettsial genes (gltA and ompA). In relation to hantavirus, rodent serum samples were serologically screened by IgG ELISA using the Araraquara-N antigen and total RNA was extracted from lung samples of IgG-positive rodents. The amplification of the complete S segment was performed. Results: A total of 153 wild rodents, 121 louse, and 36 tick specimens were collected in 2010. Laguna Negra hantavirus was identified in Calomys callidus rodents and Rickettsia bellii, Rickettsia amblyommii were identified in Amblyomma cajennense ticks. Conclusions: Zoonotic diseases such as HCPS and spotted fever rickettsiosis are a public health threat and should be considered in outbreaks and acute febrile illnesses among Indian populations. The presence of the genome of rickettsias and hantavirus in animals in this Indian reserve reinforces the need to include these infectious agents in outbreak investigations of febrile cases in Indian populations

Characterizing the neural signature of face processing in Williams syndrome via multivariate pattern analysis and event related potentials

Face recognition ability is often reported to be a relative strength in Williams syndrome (WS). Yet methodological issues associated with the supporting research, and evidence that atypical face processing mechanisms may drive outcomes ‘in the typical range’, challenge these simplistic characterisations of this important social ability. Detailed investigations of face processing abilities in WS both at a behavioural and neural level provide critical insights. Here, we behaviourally characterized face recognition ability in 18 individuals with WS comparatively to typically developing children and adult control groups. A subset of 11 participants with WS as well as chronologically age matched typical adults further took part in an EEG task where they were asked to attentively view a series of upright and inverted faces and houses. State-of-the-art multivariate pattern analysis (MVPA) was used alongside standard ERP analysis to obtain a detailed characterisation of the neural profile associated with 1) viewing faces as an overall category (by examining neural activity associated with upright faces and houses), and to 2) the canonical upright configuration of a face, critically associated with expertise in typical development and often linked with holistic processing (upright and inverted faces). Our results show that while face recognition ability is not on average at a chronological age-appropriate level in individuals with WS, it nonetheless appears to be a relative strength within their cognitive profile. Furthermore, all participants with WS revealed a differential pattern of neural activity to faces compared to objects, showing a distinct response to faces as a category, as well as a differential neural pattern for upright vs. inverted faces. Nonetheless, an atypical profile of face orientation classification was found in WS, suggesting that this group differs from typical individuals in their face processing mechanisms. Through this innovative application of MVPA, alongside the high temporal resolution of EEG, we provide important new insights into the neural processing of faces in WS