All participants were undergraduate psychology students from the University of Portsmouth who collected their own time data from the four trials. Tapping scores from 20 students (including the experimenter’s own) were then collected using an opportunity sample and collated. Participants had a mean age of 30. 9 years, a range of 28 years, and a standard deviation of 10. 5 years . All were female, two of which were left handed (For raw data see Appendix 1).
The experiment used an interactive CD-ROM that had the task used already programmed onto it (Kalat, Exploring Biological Psychology, Thomson and Wadsworth, 2004). The CD was provided with the course textbook (Kalat Biological Psychology 8th edition, Thomson and Wadsworth, 2004). A computer keyboard was used as a response device. Procedure Participants were seated in front of a computer screen, asked to fill in an informed consent form and provided with standardised instructions as to how to carry out the task (See Appendix 5).
Each participant was instructed to make as many key presses on the keyboard as they could within 30 seconds. First participants were given two practice trials, and then four experimental trials. In the experimental trials they were required to tap with a finger from their right hand and then with a finger from their left hand. In the two other trials they were required to tap with their right hand and then their left hand at the same time as answering some simple questions. The number of key presses made during each of the trials was recorded by the computer program.
The experiment took no longer than five minutes, and following the experiment participants were provided with a debriefing form (see Appendix 4) telling them of the main objectives of the study. Results Descriptive Statistics Figure 1 below shows that the mean numbers of key presses differ for each hand when language is or isn’t being processed: thus supporting our hypothesis. The mean number of taps recorded decreased for both hands when talking during the task. However, it can also be seen that the mean number of key presses recorded with the left hand when talking (165) are less than those recorded with the right hand when talking (179.6), this does not support the hypothesis of left hemisphere language dominance.
Mean Number of Key Presses per Condition Figure 1. Inferential Statistics In order to test the significance of the results, a repeated measures within-subjects ANOVA was carried out. This was used because we wanted to test for a significant difference between all four levels of the independent variable where the same participants were used for all the conditions, an ANOVA allows for this comparison.