BMS Open Day – Practical experiment

Thank you for coming to the Biomedical Sciences Open Day today. We hope you enjoyed taking part in the short “Stroop Test” experiment.

You can find more background information on the Stroop test below.  A summary of the experiment you performed is presented in the Methods section. To see the results obtained today, please view the Results page. Finally, in the Discussion page, you can find a series of questions worth considering to fully discuss  our findings.

Please note all materials presented here are based on the  lesson used during the practical experiment today, created for  the digital learning platform Lt. We use this interactive platform in many of our Year 1 and Year 2 courses.

The Stroop Test

In 1935, J.R. Stroop (1897–1973) showed that information the brain receives is processed using different pathways. The Stroop test showed conflicts (or interference) occurring when specific types of information were processed. Words are read automatically. Even when we consciously try to stop reading words it is extremely difficult to do so, especially when the information (or message) given is conflicting.

The Stroop test uses the names of common colours either written in the same (facilitation condition) or a different colour (interference condition).

Facilitation condition

When the written word and the text colour used are the same (that is, there is an association between the word and the colour), it is referred to as Stroop facilitation. In this condition, most volunteers experience a decrease in reaction time when reading the word aloud.

blue red purple green blue green red purple blue

Interference condition

When the written word and the text colour used are different, it is referred to as Stroop interference. In this condition, volunteers experience an increase in reaction time when speaking aloud the colour that the word is written in. Individuals struggle to dissociate the word written from the colour used, as this requires greater cognitive processing than just reading the words.

blue red purple green blue green red purple blue

Where there is a conflict between the word and the colour it is written in, a greater effort is required to ignore the word and to focus on the actual color of the text. That is, to succeed at this task individuals must concentrate to a greater extent. It takes less time to read aloud the word of a color, regardless of what color it is written in.

Several theories have attempted to explain the Stroop phenomenon:

• The relative speed of processing theory states that individuals can read a word faster than they can name a colour. When conflicting information is sent to the brain, interference occurs as they must override their initial response of reading the word to naming the color.
• The selective attention theory states that more attention is needed to process colour, than is needed to read a word.
• The automaticity theory refers to the processes which occur beyond conscious control and attention. From a young age we are taught to read and eventually it becomes an automatic process, while tasks such as naming colours are not. Therefore, when naming the colour of a word, the brain has to override the unconscious inclination to automatically read the word.
• The parallel processing theory views processing as “system resource limits”; it is explained using both the relative speed of processing and automaticity theories. More than one cognitive operation may occur at any time, but a bottleneck occurs when attempting to produce the various responses. When the desired responses conflict, there is interference. Automatic processes require minimal cognitive effort, while controlled processes involve greater effort and cognitive resources.

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