THE EFFECT OF A MASKED STIMULUS ON THE RESPONSE TO THE MASKING STIMULUS

Four experiments are reported in which the subjects had to respond to a target that masked a preceding prime via metacontrast masking. In on e part of Experiment 1, the subjects discriminated the target's shape (square or diamond) by a motor-choice reaction, and in another part th ey had to respond with a simple reaction. The prime was neutral (circu lar) with respect to the target's shape. The data showed a facilitatio n effect. In both tasks the reaction time was reduced by the masked pr ime. However, the reduction was more pronounced with simple reaction t han with choice reaction. In the other experiments, additional primes were used with the same angular shapes as the targets. In Experiments 2 and 3, after discriminating the target's shape by a choice reaction, the subjects had to judge the prime's shape in a signal-detection tas k. While neither the d' value for discriminating the angular primes fr om the circular ones (Exp. 2) nor the d' value for distinguishing betw een the angular primes (Exp. 3) was different from zero? the choice-re action data showed a congruency effect. With a congruent prime (i.e., a prime that had the same shape as the target), the reaction times wer e reduced. With an incongruent prime, the reaction times grew. In Expe riment 4 the errors were investigated. The facilitation effect was pre sent in the RT, but not in the number of errors, whereas the congruenc y effect was present in the number, but not in the RT of errors. While the facilitation effect can be attributed either to an unspecific act ivation by the masked prime or to an influence of the prime on attenti onal processes, the congruency effect can be explained by the assumpti on that the masked prime directly activates the specific response, whi ch corresponds to the prime's shape.