Eysenck's theory of incubation: an empirical test

Eysenck's incubation of fear hypothesis that states that repeated CS-alone presentations can yield an increase in measures of fear was tested by first giving rats either a paired or an unpaired presentation of a tone CS and either a strong (3.5 mA), weak (1.05 mA) or no-shock US and then 10 daily CS-alone presentations. Over the CS-alone trials, conditioned fear, as measured by duration of freezing, latency to escape and activity scores, extinguished, rather than incubated.