This experiment investigated the Stroop effect comparing response times between naming colour ink printed in colour-associated words and colour neutral words. Previous research of two-process theories which support Stroop’s studies [cited in Edgar:2007] found that automatic processes can interfere with controlled processes. To test this interference further, colour-associated words were employed.
Results of this experiment show a statistically significant difference in condition response times, with naming the colour ink printed in colour-associated words taking longer than those in colour neutral words, providing further support for the stroop effect and two-process theories. Introduction: The environment produces a wealth of sensory information our senses can potentially pick up and process and yet only some of it is processed, the rest ignored. This cognitive selection process is known as attention.
With attentional processes seemingly needed, this would indicate the brain has limited resources to process all sensory information. A study of ‘Change blindness’ by Simons and Levin [cited in Edgar:2007] indicates that it is generalities and not specifics which are processed. This raises questions as to why this would be the case. Kahneman [cited in Edgar:2007] proposed a theory that a part of the brain, a limited-capacity central processor, has the job of evaluating bottom-up information and combining this with top-down information.
Because it has limited capacity, much of the sensory information will not be processed. However, this explanation of limited resources does not account for the brain’s ability to do more than one task at a time, for example, listening to music while driving a car. This question was investigated using dual-task studies. Posner and Boies [cited in Edgar:2007] dual-task study, a visual and auditory task performed simultaneously, had results indicating when visual and auditory stimuli presented together, response times were slower than when singularly, supporting Kahneman’s theory.
However, Mcleod’s [cited in Edgar:2007] modified study, altered the auditory response from a button press to saying ‘bip’, found no slowing of response times. The implication being that there is no one single processor, but as Navon and Gopher, 1979; Wickens, 1992 [cited in Edgar:2007] suggest, there are ‘multiple-resource’ theories of attention. However, theory consensus is the brain can cope with finite sensory information, thus filtering out incoming information. Posner [cited in Edgar:2007] posited this filtering as an ‘attentional spotlight’ which gives processing priority to only what is within the ‘visual field’.
Eriksen and Murphy [cited in Edgar:2007] expanded this, suggesting a ‘zoom lens’ which the brain has control over, known as selective attention. There is also as Treisman [cited in Edgar:2007] discovered, situational meaning which can focus attention, for example, hearing one’s name from a conversation across a room at a party. Attentional spotlight focuses can also be involuntary or automatic, for example, a sudden loud noise leading attention away from where it was, referred as stimulus-induced shifts of attention.
This process is supported by studies from Schneider and Shiffrin [cited in Edgar:2007] suggesting an automatic process, which uses no processing resources. Given limited resources, this process frees attention for other things. These notions initiated ‘two-process theories’, suggesting controlled and automatic processes working simultaneously and efficiently, with stability circumstance dependent. However, automatic processes have downsides, as an occurrence known as the Stroop effect shows.
One example of a Stroop experiment, is a list of colour printed words, where one condition contains colour words printed in different colours, the stroop condition, and the other condition has colour neutral words printed in the same colours. Participants are required to say the colour each word is printed in as quickly as possible. The Stroop condition has significant response interference naming the colour over the neutral word condition. This raises questions. Reading is the automatic process, naming the colour is the controlled, but on that basis both conditions are the same.
Perhaps there is interference from colour words and the colour of the ink sharing similar meanings. This experiment will explore this interference further by modifying the Stroop condition, using colour-associated words instead of colour words to discover whether this produces a similar response result between Stroop and neutral conditions. The research hypothesis was that saying the colour ink printed in colour-associated words condition would take longer than in the colour neutral condition. The null hypothesis was that it would not take longer to say the colour in colour-associated words.
Method: Design – A within-participants design was used. The independent variable was naming the colour of the ink words are printed in, which incorporated two conditions, in both of which the participants had to speak aloud the colour of the ink from printed words. In condition one, the words were colour-associated and in condition two, the words were colour-neutral. The dependent variable was the time it took for the participant to complete each condition and was measured by the researcher with a stop watch to the nearest second.
To control any confounding variables, participants took part individually and all read the exact same instructions (Appendix1). The same number of words and their length were the same in both conditions. The same colour shades and the order they were used, as well as how many times each word was presented, to negate practice effects, was equal in both conditions. The order of the conditions was alternated consecutively, participant one starting with condition one and then participant two starting with condition two and so on, again to negate any practice effects.
Participants – Twenty participants, all English speaking and non colour-blind, eight of whom were men and twelve women, either fellow students at The Open University or friends and family, were asked to take part, all agreeing to volunteer. Their ages ranged from 18 to 69 years. Materials – To record the participant’s response times, for completing each condition, accurate to the nearest second, a stop watch was used. The stimuli for both conditions contained a list of six words, with condition two’s being matched in length and the first letter .
Condition one contained six colour-associated words and condition two contained six colour neutral words. Each word in both conditions was displayed five times in a matched randomised order within two columns on A4 paper. All words were printed in one of six colours, which were matched randomised. An example of the both conditions stimuli is provided in Appendix 2. Consent forms were completed by each participant (Appendix 3) and each were given the same instructions, which included an example, (Appendix 1).
A data sheet was used to record participant’s age, sex and response times (Appendix 4). SPSS software was used to acquire the statistical results. Procedure – Participants were approached individually and asked whether they would volunteer to take part in a solo cognitive psychology experiment which should last for about five minutes. The researcher then briefed the participant about the research topic being studied and why this particular experiment, answering any questions posed and mentioning there would a debrief upon completing the experiment.
Participants agreeing to take part, were informed their data would be anonymous and that they could withdraw at anytime. Upon this they signed a consent form. Then the participant’s age and sex were entered onto the data sheet, for demographic purposes only. The participant was then told they would be presented with a sheet of paper for each condition, with two columns of words and to say aloud, as quickly as they could, the colour of the ink each word was printed in, beginning with the top of the left hand column.
An example was shown to illustrate the experiment and ensure the participant fully understood what was required for them to do. For the verbatim instructions in full, please see (Appendix 1). Once the participant was content, the sheet labelled ‘Condition 1’ was placed face down in front of the participant. Upon the participant being told to turn the sheet over and begin, the researcher started the stop watch. As soon the participant completed ‘Condition 1’, the stop watch was stopped and the time to the nearest second was recorded on the data sheet. The process was repeated exactly the same way for ‘Condition 2’.
Once both conditions had been completed, the researcher thanked the participant for their time and then debriefed them as to the nature and objective of the experiment and answered any questions the participant may have had. Finally the participant was informed once again that their data would be used anonymously and that if they had any concerns at a later date, their data could be withdrawn. Results: The research hypothesis was that saying the colour ink printed in colour-associated words condition would take longer than in the colour neutral condition.
Each condition was measured for the time taken to complete saying the colour of ink printed in each word, to the nearest second. Table 1 – Mean and standard deviation for response time in seconds Mean Std. deviation Condition 1 (colour-associated words) 25. 1 6. 46 Condition 2 (colour neutral words) 21. 55 5. 4 As Table 1 shows, there is a significant difference in the mean response times for both conditions, with the mean response time for the colour-associated words condition being 3.
55 seconds longer than the colour neutral condition. A paired samples t-test was carried out and the analysis shows a statistically significant difference between the conditions, however, effect size is small, (t (19) = 4. 173; p = 0. 0005; d = 0. 254). With this result the null hypothesis was rejected. Discussion: The results of this experiment show that, on average, participants took longer naming the colour, a list of colour-associated words were printed in, than when naming the colour of a list of colour neutral words.
Suggesting the controlled process of naming the colour ink of colour-associated words, had interference from two automatic attentional processes, that of reading and association of colour. These results echo Stroop’s experiment and findings [cited in Edgar:2007] with an automatic process interfering with a controlled process, supporting Schneider and Shiffrin [cited in Edgar:2007] and two-process theories, where the balance between controlled and automatic processes is situational dependent. This situational balance leads to the modification of this experiment, using colour-associated words instead of colour words.
The participant has the automatic process of reading, interfering with the controlled process of naming the colour of the ink, but then the meaning of the word, possibly, shifts attention, effecting participant response times, similarly to Treisman [cited in Edgar:2007] findings. A possible confounding variable which could have had an affect on participants response times is if any participants had had prior knowledge of the Stroop effect, thus employing a strategy to control the automatic response as Gopher [cited in Edgar:2007] suggests that attentional control, like any skill, can be learnt and altered for a situation and or practice
effects if having taken part in a prior Stroop experiment. This may be why some of the participants had almost matched response times to both conditions, see Appendix 4. A solution to this would be to ask the participant whether they have taken part in a previous experiment and exclude them if they have. Another possible confounding variable is time of day for conducting the experiment, so standardising this would be a solution. Further studies could look at possible ways of strengthening the experiment results by increasing the number of words in the list.
Another would be to add time penalties or ask the participant to correct themselves if they make a mistake when naming the colour inks. It may be of interest to find out if age has any effect on response times. This could be done by comparing age groups. A further interesting aspect would be to conduct an experiment in which colour-associated word list response times are compared against colour word list response times, to find out whether colour-associated words have a stronger effect on participant response times than colour words.