The study found that Stroop effect and dilution are lexical in nature. The results showed that greater Stroop effect is manifested when colour word is used compared to the use of nonwords in the test. Meanwhile, Stroop dilution is higher when colour patch is flanked by a nonword stimulus than with the use of colour words.
Stroop effect manifests in a person's reaction to recognize first the written stimulus by reading it before analyzing the colour it is written. It was first reported by Stroop in 1935 (as cited in MacLeod, 1991).This is an important process in psychology since the ability to manipulate or control Stroop effect has something to do with improving the cognitive abilities of individual and increases the chances of good judgment and decisions in actual world scenarios.
Several studies prove that Stroop effect is observed in different conditions and that dilution can be performed by different parameters included in the stimulus and the stimulus itself. Different authors argue on the context of Stroop effect and the process to minimize it which is commonly referred as "Stroop dilution". Kahneman and Henik (1981) challenged the generalized notion that reading is automatic response and indispensable. They noted that if reading is automatic, it should not be affected by the placement of the word. To prove their point they found out that spatial separation between the ink colour and the incongruent colour name could reduce the strength of the Stroop effect.
The study of Kahneman and Chajczyk (1983) showed that Stroop effect is reduced when the incongruent colour word and neutral words are placed to the side (flanks) of the colour patch. Their findings challenged the notion that processing the meaning of a word is automatic. They noted that interference attributed to the Stroop effect required attention and that spreading the attention in more locations causes reduction of the Stroop effect.
Cho, Lien, and Proctor (2006) found out that neutral words can reduce the Strop effect when they serve as colour carrier, but not when the colour word was the colour carrier. They argue that Stroop dilution is due to attentional competition between the colour word and the neutral word, with priority given to the colour carrier. The finding is based on the fact that both colour carrier and neutral words are colour words.
Studies suggested that Stroop dilution is nothing to do with reading, but it is merely due to diversion and visual interference. Brown, Roos-Gilbert, & Carr (1995) reported that the reduction of the Stroop effect does not differ when words or symbols are used. The idea could be true since Stroop dilution studies use tachistoscopic presentation that limits the role of eye movements. If this is true the result of Cho, Lien, and Proctor's (2006) study may not be affected if the stimuli used are nonword.
If in the aforementioned cases the Stroop dilution was a result of a limited visual search as brought by tachistoscopic process, then the effect should disappear when a person scans thru a list. If otherwise, then Stroop dilution would be shown when a person looked at lists of words.
In the other hand, Roberts and Besner