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Poster #218 - The development of emotion discrimination in infants, children, and adults using Fast Periodic Visual Stimulation

Fri, March 22, 12:45 to 2:00pm, Baltimore Convention Center, Floor: Level 1, Exhibit Hall B

Integrative Statement

Background
The ability to detect brief changes in our environment is key for successful social communication. How these changes are detected in the human brain remains a complex puzzle. Understanding the development of the neural systems that support this ability is particularly difficult because existing measures are either ill-suited to testing very young ages (e.g., fMRI) or leave us unable to directly compare across age groups (e.g., ERP). For example, certain ERP components are observed in adults but not in infants and children (i.e., the N170, Bentin et al, 1996), and vice versa, which makes it difficult to examine ERP responses developmentally.
In the current study, we recorded brain activity using electroencephalogram (EEG) while infants, children, and adults were presented with stimuli at a frequency rate of 6Hz (1 stimulus every ~167ms). This method of rapid presentation is known as Fast Periodic Visual Stimulation (FPVS; Rossion 2014) and elicits a strong response at the presentation frequency. Participants completed an emotion discrimination task where they were presented with a happy facial expression at a base rate of 6Hz; every fifth face presented was an oddball fearful facial expression. If participants were capable of detecting the change in facial expression, this would result in an oddball response at 1.2Hz (6Hz/5).
Based on past behavioural and neural work, we hypothesized 7-month-old infants, 5- to 10-year-old children, and adults would detect the expression change, evidenced by a high Signal-to-Noise Ratio (SNR) at both the base frequency and its harmonics (i.e., 6Hz, 12Hz, 18Hz, etc.) and the oddball frequency and its harmonics (i.e., 1.2Hz, 2.4Hz, 3.6Hz, etc.).
Results
In adults (n=33), responses at both the base (6Hz) and oddball frequencies (1.2Hz) were significantly larger than surrounding frequency bins (Figure 1). Thus, adults were capable of discriminating the emotional expressions at the rapid presentation rate used here. In infants (n=33), we found a significantly larger response at the base frequency (6Hz). However, there was no significant oddball response (Figure 2), suggesting infants’ brains did not detect the brief change in expression. Data collection for the child sample is ongoing.
Implications
Based on both behavioural and ERP work (i.e., Barrera & Maurer, 1981; de Haan & Nelson, 1997), we hypothesized infants would show evidence of emotion discrimination; surprisingly, they did not. It is possible that the neural system at this age is unable to detect brief changes in emotional expression presented at such a fast rate. Results from the child sample will help us to understand the development of emotion processing.
The current study is a first attempt to use FPVS to examine neural responses to emotional expressions across several age groups. A strength of FPVS is that it is implicit and recorded in the absence of overt behavioural responses, separating it from decisional process (Rossion & Jacques, 2012), making it a promising method for infants and clinical populations. As such, FPVS offers new avenues of research for examining phenomena beyond face and emotion perception.

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