Papers by Renaud Brochard
Attention, Perception, & Psychophysics
Although several studies have reported relaxing and stimulating effects of odors on physiology an... more Although several studies have reported relaxing and stimulating effects of odors on physiology and behavior, little is known about their underlying mechanisms. It has been proposed that participant expectancy could explain these activation effects. Since emotional stimuli are known to modulate time perception, here we used the temporal bisection task to determine whether odors have objective relaxing and stimulating effects by respectively slowing down or speeding up the internal clock and whether prior expectancy could alter these effects. In Experiment 1, 118 participants were presented either with a strawberry odor or an odorless blank. In Experiment 2, 132 participants were presented either with a lemon odor or an odorless blank. In both experiments, expectancy was manipulated using suggestion (verbal instructions). The stimulus was either described as relaxing or stimulating, or was not described. In the absence of prior suggestion, findings showed that, compared to participants presented with an odorless blank, participants presented with the strawberry odor underestimated sound durations (i.e., a relaxing effect) whereas participants presented with the lemon odor overestimated them (i.e., a stimulating effect). These results confirm that pleasant odors can have objective relaxing and stimulating effects by themselves, which are better explained by arousal-based mechanisms rather than attentional distraction. Furthermore, in both experiments, incongruent suggestions undid the effects of both odors without reversing them completely (i.e., strawberry did not become stimulating even if participants were told so). Both these bottom-up and top-down influences should be considered when investigating the emotional impact of odors on human behavior.
Aging, Neuropsychology, and Cognition
Child Development
Self-biases are well described in adults but remain poorly understood in children. Here, we inves... more Self-biases are well described in adults but remain poorly understood in children. Here, we investigated in 6-10 year-old children (N = 132) the self-prioritization effect (SPE), a self-bias which reflects, in adults, the perceptual advantage for stimuli arbitrarily associated with the self as compared to those associated with other persons. We designed a child-friendly adaptation of a paradigm originally introduced in adults by Sui, He, and Humphreys (2012) in order to test whether the SPE also occurs in children and if so, to determine its evolution with age. A robust SPE was obtained from the age of 6, and this effect was similar-sized in our four age groups. These findings are discussed with reference to the development of the self during childhood.
Swiss Journal of Psychology
. This study measured the effect of emotional states on lexical decision task performance and inv... more . This study measured the effect of emotional states on lexical decision task performance and investigated which underlying components (physiological, attentional orienting, executive, lexical, and/or strategic) are affected. We did this by assessing participants’ performance on a lexical decision task, which they completed before and after an emotional state induction task. The sequence effect, usually produced when participants repeat a task, was significantly smaller in participants who had received one of the three emotion inductions (happiness, sadness, embarrassment) than in control group participants (neutral induction). Using the diffusion model ( Ratcliff, 1978 ) to resolve the data into meaningful parameters that correspond to specific psychological components, we found that emotion induction only modulated the parameter reflecting the physiological and/or attentional orienting components, whereas the executive, lexical, and strategic components were not altered. These results suggest that emotional states have an impact on the low-level mechanisms underlying mental chronometric tasks.
Annales De La Fondation Fyssen, 2000
Psychologie Francaise, 2003
Even within equitone isochronous sequences, listeners report perceiving some grouping and accenti... more Even within equitone isochronous sequences, listeners report perceiving some grouping and accenting of sound events. In a previous study we explored this phenomenon of "subjective rhythmisation" physiologically through brain event-related potentials (ERP). We found differences in the ERP responses to small loudness deviations introduced in different positions of isochronous sequences, even though all sound events were physically identical. These differences seemed to follow a binary pattern, with larger amplitudes in the response elicited by deviants in odd-numbered than in even-numbered positions. The experiments reported here were designed to test whether the differences observed corresponded to a metrical pattern, by using a similar design in sequences of a binary (long-short) or a ternary (long-short-short) meter. We found a similar pattern of results in the binary condition, but a different one, and less clear, in the ternary one. Moreover, the amplitude of the ERP re...
Journal of Psychophysiology
Previous findings on streaming are generalized to sequences composed of more than 2 subsequences.... more Previous findings on streaming are generalized to sequences composed of more than 2 subsequences. A new paradigm identified whether listeners perceive complex sequences as a single unit (integrative listening) or segregate them into 2 (or more) perceptual units (stream segregation). Listeners heard 2 complex sequences, each composed of 1, 2, 3, or 4 subsequences. Their task was to detect a temporal irregularity within 1 subsequence. In Experiment 1, the smallest frequency separation under which listeners were able to focus on 1 subsequence was unaffected by the number of co-occurring subsequences; nonfocused sounds were not perceptually organized into streams. In Experiment 2, detection improved progressively, not abruptly, as the frequency separation between subsequences increased from 0.25 to 6 auditory filters. The authors propose a model of perceptual organization of complex auditory sequences.
Consciousness and Cognition, 2015
Here we question the mechanisms underlying the emergence of the feeling of control that can be mo... more Here we question the mechanisms underlying the emergence of the feeling of control that can be modulated even when the feeling of being the author of one's own action is intact. With a haptic robot, participants made series of vertical pointing actions on a virtual surface, which was sometimes postponed by a small temporal delay (15 or 65ms). Subjects then evaluated their subjective feeling of control. Results showed that after temporal distortions, the hand-trajectories were adapted effectively but that the feeling of control decreased significantly. This was observed even in the case of subliminal distortions for which subjects did not consciously detect the presence of a distortion. Our findings suggest that both supraliminal and subliminal temporal distortions that occur within a healthy perceptual-motor system impact the conscious experience of the feeling of control of self-initiated motor actions.
Recent studies have reported that the oscillations of auditory attention entrained by a backgroun... more Recent studies have reported that the oscillations of auditory attention entrained by a background rhythmic sequence can influence performance in visual recognition tasks. We have designed an experimental paradigm in which a visual item (either a bisyllabic word or a familiar face) is displayed on screen in two consecutive parts while a musical rhythm is played in the background. Depending on the timing conditions, the first or the second part of the item could be presented either in-synchrony or out-of-synchrony with the beats of the auditory rhythm. In a first series of experiments, participants performed a lexical decision task on bisyllabic 5-letter strings. Results show that when the correct first syllable of a visual word (e.g., pan in pan.da) is presented on-beat, recognition is significantly enhanced compared to an offbeat presentation. However, if an incongruent first syllable (e.g., pa in pan.da) is presented on-beat, word recognition is highly impaired. This kind of interaction between the syllabic segmentation and rhythmic synchrony was not observed for the second part of the word. In this case, synchrony only had a positive main effect on word recognition. Overall, these results show that cross-modal temporal expectations not only affect perceptual or motor levels of processing stages but also impact more central stages of word recognition such as the processing of the first syllable. In a second series of experiments (still under way), we wanted to confirm these results using different visual materials. Here, participants had to report if the upper part of a face (containing the eyes) belonged to a familiar person or not, whether the lower part (containing the mouth) was congruent or not with the person to be recognized. Preliminary results show that the recognition of faces that are segmented in time could also be influenced by the oscillations of auditory rhythmic attention.
NeuroImage, 2018
Efficient decoding of even brief and slight intensity facial expression changes is important for ... more Efficient decoding of even brief and slight intensity facial expression changes is important for social interactions. However, robust evidence for the human brain ability to automatically detect brief and subtle changes of facial expression remains limited. Here we built on a recently developed paradigm in human electrophysiology with full-blown expressions (Dzhelyova et al., 2017), to isolate and quantify a neural marker for the detection of brief and subtle changes of facial expression. Scalp electroencephalogram (EEG) was recorded from 18 participants during stimulation of a neutral face changing randomly in size at a rapid rate of 6 Hz. Brief changes of expression appeared every five stimulation cycle (i.e., at 1.2 Hz) and expression intensity increased parametrically every 20 s in 20% steps during sweep sequences of 100 s. A significant 1.2 Hz response emerged in the EEG spectrum already at 40% of facial expression-change intensity for most of the 5 emotions tested (anger, disg...
Journal of Vision, 2015
When a background auditory rhythm is played, visual objects are processed faster when presented i... more When a background auditory rhythm is played, visual objects are processed faster when presented in synchrony with the beat than out of synchrony, reflecting the oscillating entrainment of attention (Brochard et al., 2013; Escoffier et al., 2010). The present study aimed to investigate whether attentional entrainment induced by an irrelevant rhythm modulates the holistic perception of faces by using the composite face illusion. Participants had to judge whether the top half of a face belonged to "Nicolas Sarkozy". Three conditions were used: "same" (the bottom half of the face also belongs to "Nicolas Sarkozy"),"bottom different" (the bottom half belongs to an unknown person), "different" (both halves belong to an unknown person). The two parts of the face were aligned or misaligned. A rhythm was played during the task and the onset of faces was in-synchrony (on-beat) or out-of-synchrony (off-beat). Results showed the composite face effect in accuracy: i.e., deteriorated performance for recognizing "Nicolas Sarkozy" in the upper part of the face when it is aligned with the lower part of another face as compared to misaligned. No main effects or interactions involving synchrony were found in accuracy. Interestingly, in correct RTs, the composite face effect (i.e., slower processing for aligned "bottom different" faces than misaligned ones) interacted with synchrony, as it was observed only when faces were presented on-beat. Indeed, shorter responses were found for misaligned "bottom different" faces presented on-beat as compared to off-beat, whereas synchrony did not speed up responses for aligned "bottom different" composite faces (i.e., the ones eliciting the illusion). Because correct RTs in this condition reflect the time needed to accurately recognize the upper part of the face without taking into account the misleading lower part, the present results suggest that auditory entrainment of attention might enhance the holistic perception of faces. Meeting abstract presented at VSS 2015.
Journal of Experimental Psychology-learning Memory and Cognition, 2011
The role of gender categories in prototype formation during face recognition was investigated in ... more The role of gender categories in prototype formation during face recognition was investigated in 2 experiments. The participants were asked to learn individual faces and then to recognize them. During recognition, individual faces were mixed with faces, which were blended faces of same or different genders. The results of the 2 experiments showed that blended faces made with learned individual faces were recognized, even though they had never been seen before. In Experiment 1, this effect was stronger when faces belonged to the same gender category (same-sex blended faces), but it also emerged across gender categories (cross-sex blended faces). Experiment 2 further showed that this prototype effect was not affected by the presentation order for same-sex blended faces: The effect was equally strong when the faces were presented one after the other during learning or alternated with faces of the opposite gender. By contrast, the prototype effect across gender categories was highly sensitive to the temporal proximity of the faces blended into the blended faces and almost disappeared when other faces were intermixed. These results indicate that distinct neural populations code for female and male faces. However, the formation of a facial representation can also be mediated by both neural populations. The implications for face-space properties and face-encoding processes are discussed.
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Papers by Renaud Brochard