Facial expressions perceived by the adolescent brain: Towards the proficient use of low spatial frequency information

The age bias in labeling facial expressions in children: Effects of intensity and expression

Emotion reasoning, including labeling of facial expressions, is an important building block for a child's social development. This study investigated age biases in labeling facial expressions in children and adults, focusing on the influence of intensity and expression on age bias. Children (5 to 14 years old; N = 152) and adults (19 to 25 years old; N = 30) labeled happiness, disgust or sadness at five intensity levels (0%; 25%; 50%; 75%; and 100%) in facial images of children and adults. Sensitivity was computed for each of the expression-intensity combinations, separately for the child and adult faces. Results show that children and adults have an age bias at low levels of intensity (25%). In the case of sadness, children have an age bias for all intensities. Thus, the impact of the age of the face seems largest for expressions which might be most difficult to recognise. Moreover, both adults and children label most expressions best in adult rather than child faces, leading to an other-age bias in children and an own-age bias in adults. Overall, these findings reveal that both children and adults exhibit an age bias in labeling subtle facial expressions of emotions.

The Predictive Role of Low Spatial Frequencies in Automatic Face Processing: A Visual Mismatch Negativity Investigation

Visual processing is thought to function in a coarse-to-fine manner. Low spatial frequencies (LSF), conveying coarse information, would be processed early to generate predictions. These LSF-based predictions would facilitate the further integration of high spatial frequencies (HSF), conveying fine details. The predictive role of LSF might be crucial in automatic face processing, where high performance could be explained by an accurate selection of clues in early processing. In the present study, we used a visual Mismatch Negativity (vMMN) paradigm by presenting an unfiltered face as standard stimulus, and the same face filtered in LSF or HSF as deviant, to investigate the predictive role of LSF vs. HSF during automatic face processing. If LSF are critical for predictions, we hypothesize that LSF deviants would elicit less prediction error (i.e., reduced mismatch responses) than HSF deviants. Results show that both LSF and HSF deviants elicited a mismatch response compared with their equivalent in an equiprobable sequence. However, in line with our hypothesis, LSF deviants evoke significantly reduced mismatch responses compared to HSF deviants, particularly at later stages. The difference in mismatch between HSF and LSF conditions involves posterior areas and right fusiform gyrus. Overall, our findings suggest a predictive role of LSF during automatic face processing and a critical involvement of HSF in the fusiform during the conscious detection of changes in faces.

Reward Processing in Children With Psychotic-Like Experiences

Alterations to striatal reward pathways have been identified in individuals with psychosis. They are hypothesized to be a key mechanism that generate psychotic symptoms through the production of aberrant attribution of motivational salience and are proposed to result from accumulated childhood adversity and genetic risk, making the striatal system hyper-responsive to stress. However, few studies have examined whether children with psychotic-like experiences (PLEs) also exhibit these alterations, limiting our understanding of how differences in reward processing relate to hallucinations and delusional ideation in childhood. Consequently, we examined whether PLEs and PLE-related distress were associated with reward-related activation in the nucleus accumbens (NAcc). The sample consisted of children (N = 6718) from the Adolescent Brain Cognitive Development (ABCD) study aged 9-10 years who had participated in the Monetary Incentive Delay (MID) task in functional MRI. We used robust mixed-effects linear regression models to investigate the relationship between PLEs and NAcc activation during the reward anticipation and reward outcome stages of the MID task. Analyses were adjusted for gender, household income, ethnicity, depressive symptoms, movement in the scanner, pubertal development, scanner ID, subject and family ID. There was no reliable association between PLEs and alterations to anticipation- or outcome-related striatal reward processing. We discuss the implications for developmental models of psychosis and suggest a developmental delay model of how PLEs may arise at this stage of development.

Anodal tDCS of right temporo-parietal junction promotes threat detection in low-spatial-frequency channels

Fast detection of threat is crucial for survival. Previous studies have suggested the involvement of low- and high-spatial-frequency (LSF and HSF) information in the process of threat detection. However, the specific contributions of LSF and HSF information to it are still controversial. Here we probed this issue by utilizing a prime procedure coupled with the transcranial direct current stimulation (tDCS) technique. Specifically, in a single-blind design, participants were exposed to LSF or HSF faces prior to the presentation of looming or receding spheres. Meanwhile, tDCS was applied over the right or left temporo-parietal junction (TPJ), which has been found to be preferentially associated with the processing of LSF and HSF information, respectively. The results showed significant LSF-related facilitation of threat detection when anodal tDCS was applied to the right TPJ. However, HSF-related facilitation of threat detection was not observed when anodal tDCS was applied to the left TPJ. The findings support the idea that LSF information can facilitate threat detection, and provide direct evidence that the right TPJ is vital for LSF-related facilitation of threat detection.

The Complex Emotion Expression Database: A validated stimulus set of trained actors

The vast majority of empirical work investigating the mechanisms supporting the perception and recognition of facial expressions is focused on basic expressions. Less is known about the underlying mechanisms supporting the processing of complex expressions, which provide signals about emotions related to more nuanced social behavior and inner thoughts. Here, we introduce the Complex Emotion Expression Database (CEED), a digital stimulus set of 243 basic and 237 complex emotional facial expressions. The stimuli represent six basic expressions (angry, disgusted, fearful, happy, sad, and surprised) and nine complex expressions (affectionate, attracted, betrayed, brokenhearted, contemptuous, desirous, flirtatious, jealous, and lovesick) that were posed by Black and White formally trained, young adult actors. All images were validated by a minimum of 50 adults in a 4-alternative forced choice task. Only images for which ≥ 50% of raters endorsed the correct emotion label were included in the final database. This database will be an excellent resource for researchers interested in studying the developmental, behavioral, and neural mechanisms supporting the perception and recognition of complex emotion expressions.