The influence of the preceding conditioned reaction on the current conditioned performance was studied. Rats were trained to perform delayed and non-delayed spatial tasks in Y-maze. Two types of errors were analyzed: 1) the rats ran to the same maze arm as in the previous trial (errors of repetition), 2) the animals ran to the other arm (errors of alternation). It was shown that the alternation errors were more frequent under conditions of short intertrial interval and non-delayed choice. The repetition errors occurred more frequently under conditions of long intertrial interval and delayed choice. The obtained evidence supports the idea that not only cue presentation and delay periods are important for successful performance but the whole structure of the task influences the complex organization of the behavioural acts.