Emotion perception, but not affect perception, is impaired with semantic memory loss

Abstract

For decades, psychologists and neuroscientists have hypothesized that the ability to perceive emotions on others' faces is inborn, prelinguistic, and universal. Concept knowledge about emotion has been assumed to be epiphenomenal to emotion perception. In this article, we report findings from 3 patients with semantic dementia that cannot be explained by this "basic emotion" view. These patients, who have substantial deficits in semantic processing abilities, spontaneously perceived pleasant and unpleasant expressions on faces, but not discrete emotions such as anger, disgust, fear, or sadness, even in a task that did not require the use of emotion words. Our findings support the hypothesis that discrete emotion concept knowledge helps transform perceptions of affect (positively or negatively valenced facial expressions) into perceptions of discrete emotions such as anger, disgust, fear, and sadness. These findings have important consequences for understanding the processes supporting emotion perception.

Figure 1. MRI scans of patients EG, FZ and CP

T1-weighted MRI scans of (a) patient EG (b) patient FZ (c) and patient CP showing left-lateralized anterior temporal lobe atrophy; images are shown in radiological orientation (the left hemisphere appears on the right hand side of the image).

Figure 2. Example of face stimuli

Examples of face stimuli from the IASLab set used in the face sort tasks.

Figure 3. Examples of a control participants’ performance on the free sort task

A 69-year old man made six piles to represent the six categories.

Figure 4. Patient’s performance on the emotion free sort task

In EG’s free sort, the first pile contained predominantly happy faces, the second pile contained predominantly neutral faces and the third pile contained predominantly negative faces (scowling, pouting, wide-eyed and wrinkle-nosed faces). In FZ’s free sort, the first pile contained all happy faces, the second pile contained all neutral faces, and the third and fourth piles contained all negative faces. In CP’s free sort, the first pile contained predominantly happy faces, the second pile contained all neutral faces, and the third and fourth piles contained all negative faces.

Figure 5

When asked to sort faces into six piles anchored with the numbers 1–6, CP created one pile for positive faces, one for neutral faces and four for negative faces. This task indicated the instability in her sorting from one instance to the next.