Stroop experiment using neutral and colour associated words

The aim of this experiment is to study automatic and controlled processes by replicating the previously carried out Stroop effect. This paper investigates if colour related words have a effect on automatic and controlled processes. Previous research into the subject have revealed that recognition of colour named words will have the desired effect.

The experiment was conducted by recruiting 20 participants aged between 18-68.

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Two lists of words were presented to the participants, one list of colour-associated words and another ink colour neutral words, they were timed and the data recorded for length taken in identifying the colour of each word.

The results found that it took longer to identity colour associated words then neutral ink coloured words. This would indicated automatic processes have an effect on controlled processes and unconscious semantic processing were taking place.

The Stroop effect theory was first put across in 1935 by the scientist J. Ridley Stroop. The effect has been detailed as a demonstration of interference, in which the brain experiences slowed processing time because it is trying to sort through conflicting information and degrades the performance.

The Stroop effect is a test on the reaction time of a task. When the name of a colour (e.g “Yellow”) is printed in its colour and not denoted by the name, naming the colour of the word takes longer and is more prone to errors than when the colour of the ink matches the name of the colour. This is because the brain is trying to conceal the input from the printed words in order to focus on the colour of the words.

A explanation for the Stroop effect is that the subjects have automated the process of reading. In turn the colour names of the words are always processed very quickly, regardless of the colour of the ink. On the other hand, identifying colours is not a task that observers have to report on very often, and because it is not automated and is slower.

The selected words themselves have a strong influence over your ability to say the colour. The interference between the different information,(what the word say and what the are are) your brain receives causes confusion.

Two theories have been put forward which may explain the Stroop effect, these are Speed of Processing Theory and Selective Attention Theory.

Speed of Processing is the interference which occurs because words are read faster than colours are identified.

Selective Attention is the interference which occurs because identifying colours requires more attention than reading words.

Stroop had described the complication in identifying ink colours colour named words. He cited that the identity of the colour words were interfering with the perception of ink coloured word. Richard Shiffrin and Walter Schneider, two scientists construed that reading is a automatic process and can be a unconscious action and so intrudes on an frequent procedure. Shiffrin, R. M. & Schneider, W. (1977). Controlled and automatic human information processing: II. p130.

This report details a modified version of the original experiment to investigate the Stroop effect, that being the interference of a controlled process by the use an automatic process. Schneider and Schiffrin, offer researched evidence that automatic processes are less persistent on the attention capacity and processing resources than conscious processes are. These lead to believe that, automatic and controlled processes are operating simultaneously. Shiffrin and Schneider identified certain basic properties of the automatic processes, these were they are virtually free of capacity limitations, they operate simultaneously, require detailed training, are hard to “unlearn”, and are unrealised actions. Reading is such a procedure, it takes a great amount of practice but eventually becomes automatic.

The hypothesis for this experiment is to re run the Stroop effect, and to appraise the encroachment of automatic, unconscious semantic processing.In this variation of the Stroop effect however, the experimental conditions that will be employed is a list of colour-related words (e.g. “Sky”, “Blood”). The control condition will display a list of neutral ink coloured words (“Sty”, “Blame”).

The words in the list in Stroop condition describe things that are defined by their colour and do not intrinsically refer to colours themselves.

The prediction is that the experimental hypothesis will be the time taken to identify the ink colours of a list of colour related words will be longer than that of the control list of neutral words. The null hypothesis for the experiment is that there will not be a difference in time for the completion of the two lists.

Word Count: 600

Method Section

There were two independent variables represented by the word lists printed in various colours. One list consisted of associated names, for example “blood” was the colour “yellow” rather than “red”. The second independent variable was the other list of colour ink neutral words.

The dependent variable was the time it took to identify the ink colours of the words. The number of errors in identification was also recorded.

All timings recorded were to the nearest second. condition 1 was the “Stroop” condition, condition 2 was the controlled condition. No alteration was made to the independent variables, meaning the design is parallel between the values of the dependent variables obtained from condition 1 and condition 2 for each participant.


4 participants volunteered to take part in the study(excluding OU present data). The participants were recruited from Brighton University, they consisted of Staff and Students. The participants consisted of 2 females and 2 males between the ages of 18 and 68. All participants were educated to A-Level standard or higher, fully competent in English. None of the participants suffered from any visual impairment or colour blindness. 1 Participants wore glasses.


A stopwatch accurate to the nearest second was used to time how long it took each participant to complete the task. The visual stimuli present in each condition consisted a list of 6 individual words, the words were replicated 5 times completing a total list of 30 words. The words were displayed in two columns 15 to each, all on A4 paper.

The colours were randomly distributed between the words on both lists. All words were printed on white matt paper.


Before the experiment began the participants were informed they would be participating in a experiment psychological study understanding cognitive processes and they have the right to withdraw at any time. All participants were informed that their details would be anonymous.

They were handed consent form to read through and if they were happy with the information and too be involved with the experiment to give their consent and sign the form.

Participants were individually invited to sit at a desk in a quiet, well lit unused room and were asked to read a set of instructions which were placed on desk in front of them. The lists was also place faced face down on the desk with two blank sheets of paper obscuring anything the participants might be able to see through the back of the lists.

There was also a set of instruction explain the procedure for guiding them through the experiment Each participant received the same instructions.

When they were ready the participant would indicate, remove the blank sheet and turn over the first list(condition 1) from which the stopwatch watch was simultaneously started. The stopwatch was used to record the time it took them to complete the list.

The stopwatch was stopped when the participant completed reading the list and time take was recorded. The list was turned back over and re-covered.

A two minuted interval was assign between lists, after this interval was over the same procedure was conducted with the seconded list.

On completion of the second list and time recorded, the participant was informed about the reasons behind the experiment and why they may have recorded different time in each condition.

All participants asked what their time was in each condition.

Participants data was only shared with themselves and not with other participants.

No participants withdrew from the experiment. The study was conducted in compliances with the British Psychology Society’s Code of Ethics and Conduct.

Word Count: 606
Results Section

The time it took for participant completing each condition was measured to the nearest second.

The times taken by each of the 20 participants to complete the two conditions is shown in data set table which can be found in Appendices 1.

The research hypothesis was that participants will take longer to complete Stroop effect condition then the controlled condition.

From the data, the mean time in seconds for condition 1 is 25.15 seconds, whilst that for condition 2 is 22.95 seconds, 2.2 seconds less. From this it would suggest that the results meet the research hypothesis. From analysing the data its shows that the naming of ink colour for colour-related words were indeed longer than for neutral-related words.

Word Count: 119

Discussion Section

I can conclude that from analysing the results that they support the psychological research, conducted by J. Stroop, in which that it will take longer for a participant to name the ink coloured associated words (condition 1), then it will take the exact same participant to name the ink coloured neutral words (condition 2).

The null hypothesis, that there will be no difference, was rejected. This conclusion supports findings from previous research done by Stroop, Schneider and Schiffrin into the interference effects between automatic and controlled processes.

The results displayed a increase in the time taken to read the colour-related words over the neutral words and backs up the experimental hypothesis of this study.

However the experiment was small scale and the data used was limited. Stroop used 100 participant in the original experiment and recorded more then a 60% increase in the time taken to identify the ink colours of the colour named words.

The reason behind the smaller increase in this experiment could be linked to design differences. Stroop used coloured squares instead of the neutral words as the control condition. It is possible to conceive that the neutral words used in the current experiment were themselves a assistance . An altered experiment using colour squares as an additional condition could resolve this observation.

In conclusion, the results gathered generate wider support to the suggestion that automatic processes have an effect on controlled processes. With further research it might be of interest to investigate from a Neuropsychological position, using functional Magnetic Resonance Imaging to check for any new brain activity involved when carrying out automatic processors against controlled processors. Other research maybe also be carried out in areas of automatic and controlled processes for example investigating the emotional state of participants in controlled conditions.

Word Count: 462

Total Word Count: 1958
References List

Edgar, G (2007) Perception and attention. In D. Miell, A. Phoenix, & K.Thomas (Eds.), Mapping Psychology, 10-50). Miltion Keynes: The Open University.

MacLeod, C.M. (1991). Half a century of research on the stroop effect: An integrative review., 109, 520-553.

Schmit,V. & Davis, R. (1974). The role of hemispheric specialisation in the analysis of Stroop stimuli.Act Psychological, 38, 150-160.

Warren, L.R. & Marsh, G.R. (1979). Hemispheric asymmetry in the processing of Stroop stimuli

Shiffrin, R. M. & Schneider, W. (1977). Controlled and automatic human information processing: II. Perceptual learning, automatic attending, and a general theory. Psychological Review, 84, 127-190.

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