Affective picture viewing

The standard laboratory emotion induction, and the shared paradigm behind the wiki’s sharpest live disagreement.

Why this page exists

Two studies here run essentially this method with the same moderator and reach opposite conclusions — Pollatos et al. (2005) and Dunn et al. (2010) Study 1. Both show affective pictures for 6 s, both collect SAM valence and arousal per picture, both measure interoceptive accuracy by heartbeat counting, both in healthy adults. Pollatos et al. find good perceivers rate affective pictures as more arousing; Dunn et al. find no such relationship.

Holding the paradigm fixed is what makes that disagreement legible as a disagreement rather than two unrelated results — and what makes the remaining differences (extreme-groups vs unselected sampling; ECG analysed against the pictures or not) the candidate explanations. See the comparison table on pollatos-2005-interoceptive-awareness-erp.

What the paradigm reliably produces

• Affective pictures (pleasant or unpleasant) evoke larger P300s and larger late positive slow waves than neutral ones — motivated attention, on Lang’s account: motivationally relevant stimuli automatically recruit processing resources. See event-related-potentials.
• Pictures evoke cardiac deceleration as an orienting response, greater for negative content (Bradley 2000) — the effect Dunn et al. moderate by interoceptive accuracy.
• Self-rated valence separates cleanly by category; self-rated arousal is lowest for neutral and high for both affective poles.

The arousal-rating problem

Sharpest where this wiki uses the paradigm, and unremarked in both studies that use it here.

The SAM’s arousal dimension is anchored in felt bodily activation — agitation, excitement, the body being stirred up. So when the independent variable is how well a person perceives their body, the dependent variable is partly a self-report about the body. A correlation between them is exactly what a demand-characteristics or self-concept account predicts, with no perception of any picture involved.

Pollatos et al. are more exposed to this than Dunn et al.: they ran eleven heartbeat-counting intervals immediately before the picture task, which is an interoceptive-attention induction preceding the rating measure. Dunn et al. measured interoception afterward.

That the valence dimension shows nothing in either study is the reassurance here — a pure response-bias account should colour both scales — but it is not decisive, since only the arousal anchor is bodily and so only arousal is exposed to the bias in the first place.

Relation to emBODY

Worth a note, since both paradigms ask people to report emotional bodily experience. embody asks where in the body an emotion is felt and takes emotion words or vignettes as cues; affective picture viewing asks how much the body is stirred and takes photographs as cues. Neither measures the body. Nummenmaa et al. and Volynets et al. are candid that emBODY maps are subjective feeling maps with no physiological warrant; the same is true of a SAM arousal rating, and is less often said.