09 Aug The Lemon Juice Experiment

photo 3 Thank you to the 126 students and staff who took part in our Lemon Juice Test last week. You may have been wondering: what on Earth were we doing? We were gathering data to attempt an answer to this question: is personality linked to our biology?

The first thing we asked participants to do was to complete a short questionnaire to find out how introverted or extroverted they are. Introverts tend to be more quiet and to prefer doing things alone or in small groups. Extroverts are generally louder and enjoy parties and socialising in big groups.

photo 1Introverts and extroverts show differences in the Reticular Activating System (RAS) within the brain, the system responsible for regulating wakefulness and sleep-wake transitions. Several decades ago, German psychologist Hans Eysenck came up with a biologically based model for Extroversion/Introversion. According to Eysenck’s theory, the behaviors of introverts and extroverts are due to differences in stimulation of the RAS (the speed and amount of the brain’s activity). Compared with extroverts, introverts have naturally high stimulation of the RAS, and may process more information per second therefore introverts respond more strongly to stimulus than extroverts. As a result of this suggested biological connection there should be a correlation between the stimulus – the lemon juice, and the saliva production due to the personality of a participant.

photo 4The results showed a very weak correlation between saliva production and introversion and extroversion, with a correlation of 0.0662. This means that there is little to no relationship between personality and saliva production due to the stimulus of the RAS in our experiment. This may be because there is no connection or it may be because of procedural differences in how the data was collected by the groups.

Thank you all for your participation in this Level Two Psychology experiment. We appreciate that the experiment was quite strange for all those involved. Squeezing lemon juice into someone’s mouth is an intimate and awkward experience for everyone. Plus, cotton balls do not taste very nice, we’re sorry!