Studies have shown a positive priming effect with a short time between the prime and the target. The prime increases the performance on the target if they are congruent and decreases the performance when they are incongruent. Paradoxically, a negative priming effect has been found with a long time between the prime and the target. A major hypothesis argues that the prime initiates a motor self-inhibitory process that causes these effects. This hypothesis has been criticized and the model based on this hypothesis does not fit human data. A model was developed that fits the human data. It depends on attentional neuro-modulation not motor self-inhibition.