ARTICLE UPDATE - Emotion perception in emotionless face images suggests a norm-based representation.

Neth D, Martinez AM.

Journal of Vision, 9, 5.1 - 5.11

Perception of facial expressions of emotion is generally assumed to correspond to underlying muscle movement. However, it is often observed that some individuals have sadder or angrier faces, even for neutral, motionless faces. Here, we report on one such effect caused by simple static configural changes. In particular, we show four variations in the relative vertical position of the nose, mouth, eyes, and eyebrows that affect the perception of emotion in neutral faces. The first two configurations make the vertical distance between the eyes and mouth shorter than average, resulting in the perception of an angrier face. The other two configurations make this distance larger than average, resulting in the perception of sadness. These perceptions increase with the amount of configural change, suggesting a representation based on variations from a norm (prototypical) face.

ARTICLE UPDATE - Decoding face information in time, frequency and space from direct intracranial recordings of the human brain.

Tsuchiya N, Kawasaki H, Oya H, Howard MA 3rd, Adolphs R.

PLoS One, in press

Faces are processed by a neural system with distributed anatomical components, but the roles of these components remain unclear. A dominant theory of face perception postulates independent representations of invariant aspects of faces (e.g., identity) in ventral temporal cortex including the fusiform gyrus, and changeable aspects of faces (e.g., emotion) in lateral temporal cortex including the superior temporal sulcus. Here we recorded neuronal activity directly from the cortical surface in 9 neurosurgical subjects undergoing epilepsy monitoring while they viewed static and dynamic facial expressions. Applying novel decoding analyses to the power spectrogram of electrocorticograms (ECoG) from over 100 contacts in ventral and lateral temporal cortex, we found better representation of both invariant and changeable aspects of faces in ventral than lateral temporal cortex. Critical information for discriminating faces from geometric patterns was carried by power modulations between 50 to 150 Hz. For both static and dynamic face stimuli, we obtained a higher decoding performance in ventral than lateral temporal cortex. For discriminating fearful from happy expressions, critical information was carried by power modulation between 60-150 Hz and below 30 Hz, and again better decoded in ventral than lateral temporal cortex. Task-relevant attention improved decoding accuracy more than 10% across a wide frequency range in ventral but not at all in lateral temporal cortex. Spatial searchlight decoding showed that decoding performance was highest around the middle fusiform gyrus. Finally, we found that the right hemisphere, in general, showed superior decoding to the left hemisphere. Taken together, our results challenge the dominant model for independent face representation of invariant and changeable aspects: information about both face attributes was better decoded from a single region in the middle fusiform gyrus.

ARTICLE UPDATE - EEG-MEG evidence for early differential repetition effects for fearful, happy and neutral faces.

Morel S, Ponz A, Mercier M, Vuilleumier P, George N.

Brain Research, in press

To determine how emotional information modulates subsequent traces for repeated stimuli, we combined simultaneous electro-encephalography (EEG) and magneto-encephalography (MEG) measures during long-lag incidental repetition of fearful, happy, and neutral faces. Repetition effects were modulated by facial expression in three different time windows, starting as early as 40-50 ms in both EEG and MEG, then arising at the time of the N170/M170, and finally between 280-320 ms in MEG only. The very early repetition effect, observed at 40-50 ms over occipito-temporo-parietal regions, showed a different MEG topography according to the facial expression. This differential response to fearful, happy and neutral faces suggests the existence of very early discriminative visual processing of expressive faces, possibly based on the low-level physical features typical of different emotions. The N170 and M170 face-selective components both showed repetition enhancement selective to neutral faces, with greater amplitude for emotional than neutral faces on the first but not the second presentation. These differential repetition effects may reflect valence acquisition for the neutral faces due to repetition, and suggest a combined influence of emotion- and experience-related factors on the early stage of face encoding. Finally, later repetition effects consisted in enhanced M300 (MEG) between 280 and 320 ms for fearful relative to happy and neutral faces that occurred on the first presentation, but levelled out on the second presentation. This effect may correspond to the higher arousing value of fearful stimuli that might habituate with repetition. Our results reveal that multiple stages of face processing are affected by the repetition of emotional information.

ARTICLE UPDATE - Differential effects of object-based attention on evoked potentials to fearful and disgusted faces.

Isabel M. Santos, Jaime Iglesias, Ela I. Olivares and Andrew W. Young

Neuropsychologia, in press

Event-related potentials (ERPs) were used to investigate the role of attention on the processing of facial expressions of fear and disgust. Stimuli consisted of overlapping pictures of a face and a house. Participants had to monitor repetitions of faces or houses, in separate blocks of trials, so that object-based attention was manipulated while spatial attention was kept constant. Faces varied in expression and could be either fearful or neutral (in the fear condition) or disgusted or neutral (in the disgust condition). When attending to faces, participants were required to signal repetitions of the same person, with the facial expressions being completely irrelevant to the task. Different effects of selective attention and different patterns of brain activity were observed for faces with fear and disgust expressions. Results indicated that the perception of fear from faces is gated by selective attention at early latencies, whereas a sustained positivity for fearful faces compared to neutral faces emerged around 160ms at central-parietal sites, independent of selective attention. In the case of disgust, ERP differences began only around 160ms after stimulus onset, and only after 480ms was the perception of disgust modulated by attention allocation. Results are interpreted in terms of different neural mechanisms for the perception of fear and disgust and related to the functional significance of these two emotions for the survival of the organism.

ARTICLE UPDATE - Attention for emotional faces under restricted awareness revisited: Do emotional faces automatically attract attention?

Koster EH, Verschuere B, Burssens B, Custers R, Crombez G.

Emotion, 7, 289-295

Theoretical models of attention for affective information have assigned a special status to the cognitive processing of emotional facial expressions. One specific claim in this regard is that emotional faces automatically attract visual attention. In three experiments, the authors investigated attentional cueing by angry, happy, and neutral facial expressions that were presented under conditions of limited awareness. In these experiments, facial expressions were presented in a masked (14 ms or 34 ms, masked by a neutral face) and unmasked fashion (34 ms or 100 ms). Compared with trials containing neutral cues, delayed responding was found on trials with emotional cues in the unmasked, 100-ms condition, suggesting stronger allocation of cognitive resources to emotional faces. However, in both masked and unmasked conditions, the hypothesized cueing of visual attention to the location of emotional facial expression was not found. In contrary, attentional cueing by emotional faces was less strong compared with neutral faces in the unmasked, 100-ms condition. These data suggest that briefly presented emotional faces influence cognitive processing but do not automatically capture visual attention.