The Role of Awareness in Differential Delay Eyeblink Classical Conditioning

Abstract

Eyeblink classical conditioning (EBCC) is an experimental procedure widely used for understanding learning and memory in a variety of species. In EBCC, a neutral conditioned stimulus (CS; a tone) is repeatedly paired with an unconditioned stimulus (US; a corneal airpuff). Following repeated presentations, the CS alone begins to elicit an eyeblink, known as the conditioned response (CR). The CR is taken as evidence that the animal has formed a lasting association between the CS and US. However in humans, whether this form of learning depends on conscious awareness of the CS-US relationship has been largely debated. One possibility for this debate is that during differential delay EBCC, awareness may be necessary when the CSs are difficult to discriminate. The aim of the current study was to test this prediction in three groups of participants by manipulating the discriminability of tones (CSs) within a differential delay EBCC procedure and probing participant’s awareness of the CS-US relationship. In Group I, 1000 Hz tone and white noise were used as CSs, whereas in Groups II and III, 1000 Hz vs 1400 Hz and 1000 Hz vs 1150 Hz tones were used as CSs respectively. Both aware and unaware participants demonstrated differential conditioning in Group I suggesting that awareness was not necessary for differential conditioning. In Group II, aware participants demonstrated early conditioning compared to unaware participants. However, in Group III no participants (aware and unaware) demonstrated conditioning suggesting that awareness was not sufficient for successful differential conditioning.