Interference and facilitation are two important aspects of automatic processes. Interference refers to the range to which one process encumbers performance of another, whereas facilitation indicates the extent to which one process assists performance of another.
Through practice and maturation, reading progresses from a controlled process to one that is automatic, lessening the demands on attentional resources. Stroop reported one of the first studies, which provided support for this, in 1935. He combined the word object/property dimensions in the same stimulus to create one of the most researched phenomena in cognitive psychology: The Stroop effect (MacLeod, 1991). He found that it was faster to read words than it was to name the corresponding object or their properties, including their color.
Due to its key in understanding attention, the study that lead to many other related investigations, originated by examining interference in reading automaticity. Stroop furthered his research by creating tasks involving color naming and reading. He first compared the time it took to read color names printed in incongruent ink colors to a base line reading of color words. For the second part of his study, Stroop compared the time it took to name the ink color when congruent with the color word (e.g., blue printed in blue ink) to the time it took to name the ink color.
By comparing the response times in the interference conditions to the control conditions he found that it took people longer to respond to the color of the ink when printed in a color incongruent to the color word (Stroop, 1995). The words interfere with naming the color; yet, the color does not interfere with reading the word.
The nature of the Stroop effect results as a consequence of automaticity. People have difficulty ignoring the meaning of a word because, through practice, reading has become an automatic process. The two main explanations