Attentional blink startle modulation during pleasant and unpleasant cues in human affective conditioning

Affect modulates the startle blink reflex in a linear fashion in the picture-viewing paradigm. However, the process responsible for reflex modulation during conditional stimuli (CSs) that have acquired valence through affective conditioning remains unclear. Experiments 1 – 3 conditioned positive and negative valence to neutral stimuli (CSs) using the picture-picture paradigm. Pleasantness ratings and affective priming were used as indices of CS valence changes. Startle modulation was assessed throughout an extinction phase: acoustic startle-eliciting probes were presented at long lead intervals during CSs and during inter-trial intervals. Experiment 1 used a between-group design to condition positive and negative valence separately in a differential conditioning procedure. Experiment 2 and 3 employed pleasant, unpleasant, and neutral USs within a single procedure. In Experiment 2 picture pairs were presented in a standard forward conditioning(CS-US) manner, whereas in Experiment 3 the stimuli were presented in a backward conditioning (US-CS) manner to control for a potential effect of anticipatory arousal on startle modulation. Affective learning as indexed by ratings and/or affective priming was evident in all experiments. Blink startle was larger during CSs that had been paired with valenced USs than during the neutral CS. This result emerged regardless of US valence or of the conditioning procedure. Taken together, the data strongly support an attentional modulation account of startle reflex modulation during human affective conditioning