Single prime negative priming (NP) effect is demonstrated via increase in RT to a target stimulus similar to a previously presented prime. This paper discusses the possibility of considering this effect as a consequence of the negative choice aftereffect - the tendency not to become aware of stimuli that previously had not been aware of. Such explanation implies that NP can be detected in the absence of probe distractors and also without multiple stimulus repetitions: we test this hypothesis in the experiments. We also discuss the interaction of the positive (PP) and negative priming mechanisms. It is supposed that the NP will decrease with increasing of the cognitive system "trust" to primes (due to increase of the tendencies underlying the PP). In this context, we test the influence of the previous trial congruence on the NP. Participants in our study had to recognize words (exp. 1-2) or numbers (exp. 3-4) slowly emerging on the screen. 50% of the rapidly presented primes matched the target stimuli. In the experiment 1 the increase of RT was observed when primes matched the targets. In the experiments 2-4 the negative priming was replaced by the positive priming (exp. 2) or decreased its effect (exp. 3-4) after the congruent trials.