This enabled us to test whether List 1 and List 2 items elicited different ERPs, and whether the evoked response to the items was influenced by the participants' prior experience and judgement type.
Firstly, the test phase was fairly short, consisting of 40 trials per judgement type (action or tone).
To characterize in detail the nature of the interaction between judgement type and ∆BMIi we ran separate analyses for the body size and attractiveness judgements.
The two factors were judgement type (action or visual form matching) and control demands (contrasting easy decisions about globally related items with difficult decisions based on specific features).
Mean judgement errors for each trial type (surprise/ expected) and for each judgement type (Action/ Tone) were calculated for each participant.
We again used a general linear model in which we included the effects of ∆BMIi, ∆BMIt, ∆STt, sex and judgement type.
These main effects were replicated in a single general linear model in which we modelled the effects of ∆BMIi, ∆BMIt, ∆STt, observer sex and judgement type (size or attractiveness).
Critically, there was again a significant interaction between ∆BMIi and judgement type (F1,5553 =4.02, p = 0.04), showing that there are differences in the effect of ∆BMIi on the two judgements.
