Abstract
Subjects matched the position (high or low) of a first stimulus with either the position or the meaning of a word (HI or LO) presented after an interstimulus interval (ISI). The form of the first stimulus (X or O) varied randomly within trial blocks and specified the relevant feature (meaning or position) of the second stimulus to the subject. When the relevant feature was meaning, Stroop interference from the second stimulus position was observed. This interference decreased as ISI increased. At the longest ISI, it was eliminated completely. A number of explanations for these effects are discussed and then tested in two further matching experiments. In a fourth experiment a similar decrease in interference was observed. These reductions in interference with increase in ISI appear to represent the development of attentional focusing on the relevant feature of the second stimulus. Stroop interference may occur in experiments where the relevant attribute is constant because of a difficulty associated with repeated focusing on the same attribute.
