Parallel acquisition of awareness and trace eyeblink classical conditioning

Abstract

Trace eyeblink conditioning (with a trace interval >/=500 msec) depends on the integrity of the hippocampus and requires that participants develop awareness of the stimulus contingencies (i.e., awareness that the conditioned stimulus [CS] predicts the unconditioned stimulus [US]). Previous investigations of the relationship between trace eyeblink conditioning and awareness of the stimulus contingencies have manipulated awareness or have assessed awareness at fixed intervals during and after the conditioning session. In this study, we tracked the development of knowledge about the stimulus contingencies trial by trial by asking participants to try to predict either the onset of the US or the onset of their eyeblinks during differential trace eyeblink conditioning. Asking participants to predict their eyeblinks inhibited both the acquisition of awareness and eyeblink conditioning. In contrast, asking participants to predict the onset of the US promoted awareness and facilitated conditioning. Acquisition of knowledge about the stimulus contingencies and acquisition of differential trace eyeblink conditioning developed approximately in parallel (i.e., concurrently).

Figure 1

Number of correct responses to 17 true or false questions given at the end of the conditioning session. The questions asked about the relationship between the CS⁺, the CS⁻, and the US. During the session, participants in the Predict Airpuff group pressed a button whenever they believed the US was about to occur. Participants in the Predict Eyeblink group pressed a button whenever they believed they were about to blink. Brackets show SEM.

Figure 2

(A) Percentage differential button presses across six blocks of 20 trials (the percentage of CS⁺ trials on which participants pressed the button minus the percentage of CS⁻ trials on which participants pressed the button). During the conditioning session, participants in the Predict Airpuff group pressed a button whenever they believed the US was about to occur. Participants in the Predict Eyeblink group pressed the button whenever they believed they were about to blink. (B) Percentage differential CRs across the six blocks of 20 trials (the percentage of CS⁺ trials on which participants emitted an eyeblink minus the percentage of CS⁻ trials on which an eyeblink was emitted). Brackets show SEM.

Figure 3

Percentage differential button presses and percentage differential CRs across 24 blocks of five trials for the Predict Airpuff group (n = 14). During the conditioning session, participants pressed a button to try to predict the onset of the US. Brackets show SEM.