Dissociating Affective Salience and Valence in (Very) Long-Latency ERPs

Area of Science:

• Neuroscience
• Affective Science
• Cognitive Psychology

Background:

• Affective salience effects are consistently observed in the late positive potential (LPP) but ordered valence effects in event-related potentials (ERPs) remain inconsistent.
• Previous research suggested valence-related effects at very long latencies (1000-3000 ms) using facial attractiveness stimuli, prompting further investigation into general valence effects.

Purpose of the Study:

• To investigate the existence of a long-latency valence effect in electroencephalogram (EEG) responses to general image stimuli.
• To determine if affective processing involves distinct stages of salience detection followed by valence differentiation.

Main Methods:

• Presented 224 participants with positive, neutral, and negative International Affective Picture System (IAPS) images.
• Recorded electroencephalogram (EEG) to measure event-related potentials (ERPs).
• Analyzed ERP amplitudes across different time windows to identify affective salience and valence effects.

Main Results:

• An affective salience effect (larger ERPs for positive/negative vs. neutral stimuli) was observed from approximately 500 to 1300 ms.
• A long-latency valence effect (larger ERPs for negative vs. positive stimuli) emerged between 1500 and 2500 ms.
• The polarity of the long-latency valence effect contrasted with findings from a facial attractiveness study.

Conclusions:

• Findings support a two-stage model of emotion processing, with initial affective salience detection followed by later valence differentiation.
• The results align with theories of constructed emotion, suggesting a dynamic interplay of neural processes in affective perception.
• Allostasis is proposed as a potential mechanism to reconcile differing valence effect polarities across studies.