Pupillary Responses to Faces Are Modulated by Familiarity and Rewarding Context.
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ABSTRACT: Observing familiar (known, recognisable) and socially relevant (personally important) faces elicits activation in the brain's reward circuit. Although smiling faces are often used as social rewards in research, it is firstly unclear whether familiarity and social relevance modulate the processing of faces differently, and secondly whether this processing depends on the feedback context, i.e., if it is different when smiles are delivered depending on performance or in the absence of any action (passive viewing). In this preregistered study, we compared pupillary responses to smiling faces differing in subjective familiarity and social relevance. They were displayed in a passive viewing task and in an active task (a speeded visual short-term memory task). The pupils were affected only in the active task and only by subjective familiarity. Contrary to expectations, smaller dilations were observed in response to more familiar faces. Behavioural ratings supported the superior rewarding context of the active task, with higher reward ratings for the game than the passive task. This study offers two major insights. Firstly, familiarity plays a role in the processing of social rewards, as known and unknown faces influence the autonomic responses differently. Secondly, the feedback context is crucial in reward research as positive stimuli are rewarding when they are dependent on performance.
Project description:Different kinds of known faces activate brain areas to dissimilar degrees. However, the tuning to type of knowledge, and the temporal course of activation, of each area have not been well characterized. Here we measured, with functional magnetic resonance imaging, brain activity elicited by unfamiliar, visually familiar, and personally-familiar faces. We assessed response amplitude and duration using flexible hemodynamic response functions, as well as the tuning to face type, of regions within the face processing system. Core face processing areas (occipital and fusiform face areas) responded to all types of faces with only small differences in amplitude and duration. In contrast, most areas of the extended face processing system (medial orbito-frontal, anterior and posterior cingulate) had weak responses to unfamiliar and visually-familiar faces, but were highly tuned and exhibited prolonged responses to personally-familiar faces. This indicates that the neural processing of different types of familiar faces not only differs in degree, but is probably mediated by qualitatively distinct mechanisms.
Project description:Separate event-related brain potential (ERP) components have been hypothesized to index familiarity and recollection processes that support recognition memory. A 300- to 500-ms mid-frontal FN400 old/new difference has been related to familiarity, whereas a 500- to 800-ms parietal old/new difference has been related to recollection. Other recent work has cast doubt on the FN400 familiarity hypothesis, especially its application to familiarity-based recognition of conceptually impoverished stimuli such as novel faces. Here we show that FN400 old/new differences can be observed with novel faces, and as predicted by the familiarity hypothesis, these differences are observed regardless of whether or not recognition is accompanied by the recollection of specific details from the study episode. Furthermore, FN400 differentiation between hits and misses is more consistent with an explicit familiarity process than an implicit memory process.
Project description:Previous studies have shown that prior knowledge can have both enhancing and detrimental effects on memory for relevant information. Few studies have explored the boundary conditions under which prior knowledge facilitates or interferes with memory processes. In addition, to what extent the effects of prior knowledge change over time is unclear. In this study, we addressed this question by separating category familiarity (i.e., prior conceptual knowledge) and stimulus familiarity at different retention intervals. Participants were tested with a recognition task after they learned four types of words, that is., familiar words from familiar categories (FwordFcate) and unfamiliar categories (FwordUcate) as well as unfamiliar words from familiar (UwordFcate) and unfamiliar categories (UwordUcate). The results showed a significant interaction between category familiarity and word familiarity, that is, unfamiliar words, but not familiar words, from familiar categories were remembered better than those from unfamiliar categories. The enhancing effect of category familiarity depended on the recollection process and remained stable over time. This study suggested that stimulus familiarity modulates the effects of category familiarity on memory performance, and clarified the boundary conditions for the effects of prior knowledge.
Project description:The pupil response discriminates between old and new stimuli, with old stimuli characterized by larger pupil dilation patterns than new stimuli. We sought to explore the cause of the pupil old/new effect and discount the effect of targetness, effort, recollection retrieval, and complexity of the recognition decision. Two experiments are reported in which the pupil response and the eye fixation patterns were measured, while participants identified novel and familiar object stimuli, in two separate tasks, emphasizing either novelty or familiarity detection. In Experiment 1, familiarity and novelty decisions were taken using a rating scale, while in Experiment 2 a simpler yes/no decision was used. In both experiments, we found that detection of target familiar stimuli resulted in greater pupil dilation than the detection of target novel stimuli, while the duration of the first fixation discriminated between familiar and novel stimuli as early as within 320 ms after stimulus onset. Importantly, the pupil response distinguished between the objective (during an earlier temporal component) and the subjective (during a later temporal component) status of the stimulus for misses and false alarms. In the light of previous findings, we suggest that the pupil and fixation old/new effects reflect the distinct neural and cognitive mechanisms involved in the familiarity and novelty decisions. The findings also have important implications for the use of pupil dilation and eye movement patterns to explore explicit and implicit memory processes.
Project description:BackgroundAtypical autonomic arousal has been consistently documented in autism spectrum disorder (ASD) and is thought to contribute to the social-communication phenotype of ASD. Some evidence suggests that clinically unaffected first-degree relatives of autistic individuals may also show subtle differences in indices of autonomic arousal, potentially implicating heritable pathophysiological mechanisms in ASD. This study examined pupillary responses in parents of autistic individuals to investigate evidence that atypical autonomic arousal might constitute a subclinical physiological marker of ASD heritability within families of autistic individuals.MethodsPupillary responses to emotional faces were measured in 47 ASD parents and 20 age-matched parent controls. Macro-level pupillary responses (e.g., mean, peak, latency to peak) and dynamic pupillary responses over the course of the stimulus presentation were compared between groups, and in relationship to subclinical ASD-related features in ASD parents. A small ASD group (n = 20) and controls (n = 17) were also included for exploratory analyses of parent-child correlations in pupillary response.ResultsParents of autistic individuals differed in the time course of pupillary response, exhibiting a later primary peak response than controls. In ASD parents, slower peak response was associated with poorer pragmatic language and larger peak response was associated with poorer social cognition. Exploratory analyses revealed correlations between peak pupillary responses in ASD parents and mean and peak pupillary responses in their autistic children.ConclusionDifferences in pupillary responses in clinically unaffected parents, together with significant correlations with ASD-related features and significant parent-child associations, suggest that pupillary responses to emotional faces may constitute an objective physiological marker of ASD genetic liability, with potential to inform the mechanistic underpinnings of ASD symptomatology.
Project description:Odors can increase memory performance when presented as context during both encoding and retrieval phases. Since information from different sensory modalities is integrated into a unified conceptual knowledge, we hypothesize that the social information from body odors and faces would be integrated during encoding. The integration of such social information would enhance retrieval more so than when the encoding occurs in the context of common odors. To examine this hypothesis and to further explore the underlying neural correlates of this behavior, we have conducted a functional magnetic resonance imaging study in which participants performed an encoding-retrieval memory task for faces during the presentation of common odor, body odor or clean air. At the behavioral level, results show that participants were less biased and faster in recognizing faces when presented in concomitance with the body odor compared to the common odor. At the neural level, the encoding of faces in the body odor condition, compared to common odor and clean air conditions, showed greater activation in areas related to associative memory (dorsolateral prefrontal cortex), odor perception and multisensory integration (orbitofrontal cortex). These results suggest that face and body odor information were integrated and as a result, participants were faster in recognizing previously presented material.
Project description:During the COVID-19 pandemic, the wearing of face masks became mandatory in public areas or at workplaces in many countries. While offering protection, the coverage of large parts of our face (nose, mouth and chin) may have consequences for face recognition. This seems especially important in the context of contact tracing which can require memory of familiar and unfamiliar contacts and whether they were wearing a mask. In this study, we tested how well participants perform at remembering faces and whether they wore a mask, and if this depends on familiarity. Our results show that: (a) Participants remembered familiar faces better than unfamiliar ones, regardless of mask wearing. (b) Participants remembered unmasked faces better than masked faces, regardless of familiarity. (c) Participants were significantly worse at remembering whether an unfamiliar face was wearing a mask or not-even if they indicated remembering the face. (d) Participants showed a bias to indicate no memory of unfamiliar faces. (e) Participants showed a bias to indicate that unfamiliar faces wore a mask, even if they did not. In sum, it was harder to remember both, the identity of unfamiliar faces and whether they wore a mask. These findings have practical relevance for contact tracing and epidemic control.
Project description:Background:Exploratory behaviour is one of the best-investigated behavioural traits. However, little is known about how differences in familiarity, i.e. in the knowledge and previous experience with a companion can influence the exploration of a novel environment. However, to our knowledge, such a critical feature of the social environment has never been the target of a study relating it to exploratory behaviour in birds. Here we examined if familiarity with a conspecific could affect behavioural responses of individuals confronted with a novel environment. We recorded the latency to land on the ground, latency to feed, time spent feeding and number of sectors visited of 48 female and 48 male house sparrows (Passer domesticus) in an indoor aviary in three contexts: alone (individual context), with an unfamiliar and with a familiar same-sex companion. Results:House sparrows landed sooner on the ground when in the familiar context than when in the individual context. Birds in unfamiliar pairs followed each other less than familiar birds, but this difference diminished with time spent exploring. Moreover, males and females differed in their behavioural responses in the unfamiliar context. Females with a familiar companion landed sooner than when they were paired with an unfamiliar conspecific, whereas only the presence of a companion but not familiarity reduced males latency to land on the ground. Finally, when considering the unfamiliar context males had shorter latencies to forage and thus spent more time eating than females. Conclusions:The presence or absence of a companion and its familiarity with the focal individual influenced differently the behavioural responses of male and female house sparrows in a novel environment. As house sparrows are strongly sociable, the influence of the social environment is likely to be of paramount importance to understand the selective pressures acting on them, particularly in recently colonized areas with ephemeral food sources. Our results shed light on the complex influence that the social environment has on the behavioural responses of a cosmopolitan bird.
Project description:The 'uncanny valley' response is a phenomenon involving the elicitation of a negative feeling and subsequent avoidant behaviour in human adults and infants as a result of viewing very realistic human-like robots or computer avatars. It is hypothesized that this uncanny feeling occurs because the realistic synthetic characters elicit the concept of 'human' but fail to satisfy it. Such violations of our normal expectations regarding social signals generate a feeling of unease. This conflict-induced uncanny valley between mutually exclusive categories (human and synthetic agent) raises a new question: could an uncanny feeling be elicited by other mutually exclusive categories, such as familiarity and novelty? Given that infants prefer both familiarity and novelty in social objects, we address this question as well as the associated developmental profile. Using the morphing technique and a preferential-looking paradigm, we demonstrated uncanny valley responses of infants to faces of mothers (i.e. familiarity) and strangers (i.e. novelty). Furthermore, this effect strengthened with the infant's age. We excluded the possibility that infants detect and avoid traces of morphing. This conclusion follows from our finding that the infants equally preferred strangers' faces and the morphed faces of two strangers. These results indicate that an uncanny valley between familiarity and novelty may accentuate the categorical perception of familiar and novel objects.
Project description:Measuring pupillary response is a prevalent technique to evaluate mental states. It is indispensable to conduct a correction procedure for the pupillary baseline to get a meaningful conclusion from the pupillary response. However, the relationship between pupillary baseline and subsequent stimulus-evoked pupillary response varies among studies. In this study, we used the subtractive and proportional baseline corrections to analyze the results. Furthermore, we manipulated the pupillary baseline through mental effort or luminance in the baseline period and investigated whether the subsequent stimulus-evoked pupillary responses were affected. We found that the mental effort-evoked pupillary response was attenuated with a larger pupillary baseline manipulated by a higher mental effort, whereas it was unaffected with the baseline manipulated by luminance. Also, the luminance-evoked pupillary response was attenuated with a smaller pupillary baseline manipulated by a brighter disk, whereas it was unaffected with the baseline manipulated by mental effort. The results could be obtained from subtractive and proportional baseline corrections. Our results suggest that mental effort manipulated pupillary baseline interacts with the subsequent mental effort elicited pupillary response, but not with the luminance elicited pupillary response; the luminance manipulated pupillary baseline interacts with the subsequent luminance elicited pupillary response, but not with the mental effort elicited pupillary response. It is important to consider the ways of controlling the pupillary baseline and subsequent pupillary response simultaneously.