Is Face Age Mapped Asymmetrically onto Space? Insights from a SNARC-like Task

The magnitude associated with a stimulus can be spatially connoted, with relatively smaller and larger magnitudes that would be represented on the left and on the right side of space, respectively. According to recent evidence, this space–magnitude association could reflect specific brain asymmetries. In this study, we explored whether such an association can also emerge for face age, assuming that responders should represent relatively younger and older adult faces on the left and on the right, respectively. A sample of young adults performed a speeded binary classification task aimed at categorising the age of a centrally placed adult face stimulus as either younger or older than the age of a reference face. A left-side and a right-side response key were used to collect manual responses. Overall, older faces were categorised faster than younger faces, and response latencies decreased with the absolute difference between the age of the target stimulus and the age of the reference, in line with a distance effect. However, no evidence of a left-to-right spatial representation of face age emerged. Taken together, these results suggest that face age is mapped onto space differently from other magnitudes.

Effects of color–emotion association on facial expression judgments

Color and emotion are metaphorically associated in the human mind. This color–emotion association affects perceptual judgment. For example, stimuli representing colors can affect judgment of facial expressions. The present study examined whether colors associated with happiness (e.g., yellow) and sadness (e.g., blue and gray) facilitate judgments of the associated emotions in facial expressions. We also examined whether temporal proximity between color and facial stimuli interacts with any of these effects. Participants were presented with pictures of a happy or sad face against a yellow-, blue-, or gray-colored background and asked to judge whether the face represented happiness or sadness as quickly as possible. The face stimulus was presented simultaneously (Experiment 1) or preceded for one second by the colored background (Experiment 2). The analysis of response time showed that yellow facilitated happiness judgment, while neither blue nor gray facilitated sadness judgment. Moreover, the effect was found only when the face and color stimuli were presented simultaneously. The results imply that the association of sadness with blue and gray is weak and, consequently, does not affect emotional judgment. Our results also suggest that temporal proximity is critical for the effect of the color–emotion association (e.g., yellow–happiness) on emotional judgment.

Task demands modulate effects of threatening faces on early perceptual encoding

The threat capture hypothesis states that threatening stimuli are automatically processed with higher priority than non-threatening stimuli, irrespective of the task. We evaluated the threat capture hypothesis with respect to the early perceptual stages of face processing. We focused on an electrophysiological marker of face processing (the lateralized N170) in response to neutral, happy, and angry facial expressions displayed in competition with a non-face stimulus (a house). We evaluated how effects of facial expression on the lateralized N170 were modulated by task demands. In one task, participants were required to identify the gender of the face, which made the face task-relevant and entailed structural encoding of the face stimulus. In another task, participants identified the location of a missing pixel in the fixation cross, which made the face task-irrelevant and placed it outside the focus of attention. When faces were relevant, the lateralized N170 to angry faces was enhanced compared to happy and neutral faces. When faces were irrelevant, facial expression had no effect. These results reveal the critical role of task demands on the preference for threatening faces, indicating that top-down, voluntary processing modulates the prioritization of threat.

Gaze-Cueing With Crossed Eyes: Asymmetry Between Nasal and Temporal Shifts

A person’s direction of gaze (and visual attention) can be inferred from the direction of the parallel shift of the eyes. However, the direction of gaze is ambiguous when there is a misalignment between the eyes. The use of schematic drawings of faces in a previous study demonstrated that gaze-cueing was equally effective, even when one eye looked straight and the other eye was averted. In the current study, we used more realistic computer-generated face models to re-examine if the diverging direction of the eyes affected gaze-cueing. The condition where one eye was averted nasally while the other looked straight produced a significantly smaller gaze-cueing effect in comparison with when both eyes were averted in parallel or one eye was averted temporally. The difference in the gaze-cueing effect disappeared when the position of one eye was occluded with a rectangular surface or an eye-patch. These results highlight the possibility that the gaze-cueing effect might be weakened when a direct gaze exists between the cueing eye (i.e., nasally oriented eye) and the target and the effect magnitude might depend on which type of face stimulus are used as a cue.

A face identity hallucination (palinopsia) generated by intracerebral stimulation of the face-selective right lateral fusiform cortex

We report the case of a patient (MB, young female human subject) who systematically experiences confusion between perceived facial identities when electrically stimulated inside the lateral section of the right fusiform gyrus. In the presence of a face stimulus (an experimenter or a photograph), intracerebral electrical stimulation in this region generates a perceptual hallucination of an individual facial part integrated within the whole perceived face, i.e. facial palinopsia. In the presence of a distracting stimulus (visual scene or object picture), the patient also experiences an individual face percept superimposed on the non-face stimulus. The stimulation site evoking this category-selective transient palinopsia is localized in a region showing highly selective responses to faces both with functional magnetic resonance imaging (“Fusiform Face Area”, “FFA”) and intracerebral electrophysiological recordings during fast periodic visual stimulation (FPVS). Importantly, the largest electrophysiological response to fast periodic changes of facial identity is also found at this location. Altogether, these observations suggest that a local face-selective region of the right lateral fusiform gyrus suffices to generate a vivid percept of an individual face, supporting the active role of this region in individual face representation.