Neural Correlates of Emotional Judgements

EEG

[Photo by robertrazrblog]

At the outset of this journey into the emotions, I considered the philosophical work of Robert Solomon. Recall that Solomon argues that emotions are judgements and strategies rather than experiences that well up unbidden from the deep. This post asks whether it is possible to find any empirical evidence for this attractive idea.

Using EEG recording, Hajcak, Moser & Simons (2006) investigated the way people’s physiological responses varied with the type of judgement they made to emotionally arousing stimuli. Participants were shown pictures from the International Affective Picture System three times with different instructions each time:

  • First time (or block): Participants just looked at the pictures naturally – or as naturally as you can with a load of wires attached to your scalp.
  • Second block: participants were asked to make judgements about the emotional content of the pictures
  • Third block: participants were simply asked to indicate how many people were in the image.

The recording being made in this study were via EEG and, more specifically, focussed on a particular response called the ‘late positive potential’ (LPP). To interpret their results we need to understand something about what this LPP is. Here is how Hajcak et al. (2006) describe it:

“…the enhanced LPP may relate to augmented attention to arousing stimuli [...] the LPP might, like increased blood flow in visual cortex, index the facilitated perceptual processing that results from the activation of structures such as the amygdala…” (Hajcak et al., 2006:517)

So, the theory goes that the LPP is related in some close way to emotional processing. What this study found, then, was that the LPP was greater when participants were attending to the emotional content of the images, rather than when they were attending to a non-emotional aspect. This seems to provide some nice evidence that appraisals impinge on the processing of emotions.

The use of EEG is not as sexy as fMRI but in this paradigm it has one major advantage, it is ‘temporally sensitive’. fMRI has a lag of a few seconds between activity in the brain and its measurement. EEG, on the other hand, only lags in the order of milliseconds so it is much better at telling when something has happened in the brain.

I’d like to be able to convincing connect this study with Solomon’s ideas about emotions as judgements but the two levels of discussion are just too far removed. The most we can say from this study is that it shows that appraisals (judgements) appear to play some role in emotional processes. Crucially, using EEG also tells us that these processes happen fast, suggesting they are unconscious.

Hajcak, G., Moser, J., & Simons, R. (2006). Attending to affect: appraisal strategies modulate the electrocortical response to arousing pictures. Emotion, 6(3), 517-22. (Abstract)

About the author


Dr Jeremy Dean is a psychologist and the author of PsyBlog. His latest book is "Making Habits, Breaking Habits: How to Make Changes That Stick". You can follow PsyBlog by email, by RSS feed, on Twitter and Google+.

Published: 20 November 2006

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