Figure 1 shows main effects for gender, status and a main interaction effect between gender and status.
The status main effect indicates that when the confederate drove a high status vehicle, males spent longer in their road rage reactions than when the confederate drove a low status vehicle. The differences for females depending on the status of the vehicle are shown only to be small. Overall the high status vehicle induces a longer duration of road rage. The gender main effect shows that females spend less time making verbal road rage reactions compared to males, when the vehicle was of high status; there was no major difference for low status vehicles.
Interaction effects: represent the extent to which the dependent variable is influenced by the combined effect of two or more of the independent variables.
In our example one interaction effect exists between status, gender and duration???
CHECK WITH PAUL
The results of the ANOVA indicate that duration of verbal road rage reactions were significantly affected by status of the vehicle (high status was longer), (F (1, 12) = 7.3, p < .05). Verbal road rage reactions were also significantly affected by gender (males spent longer), (F (1, 12) = p <.01) – BUT AST FROM SPSS SAYS .005?? There was also a significant interaction between status and gender (F (1, 12) = 5.9, p <.05) with the interaction graph indicating that males spent significantly longer verbalising road rage reactions than females for the high status vehicle.
3. Further analyses were conducted to further develop our knowledge of road rage. Firstly a correlation has been carried out to demonstrate the relationship between duration spent road raging and PADS score, with the hypothesis being that the longer spent verbalising road rage, the higher the PADS score.
Figure 2 shows support for this hypothesis - as duration spent road raging increases so does PADS score – demonstrating a positive relationship.
A Pearson correlation was used to test the significance of this relationship and as shown in Figure 3 it was found to be significant at the 0.01 level.
Figure 2. Scattergram of PADS score and Duration spent road raging in seconds.
Correlations
** Correlation is significant at the 0.01 level (1-tailed).
Figure 4. Pearson Correlation between duration and PADS score.
These results also demonstrate the validity of the PADS measure – the scale is measuring what it intended to measure. As we would expect the longer the duration of road rage, the angrier the participant seems to have got and as a result a higher PADS score was obtained.
In a second analysis to assess the contribution of road rage to increases in participant’s heart rate, SPSS compute was used to create a new variable of the difference between participant heart rate prior to the experiment, and participant heart rate after the experiment. Note that if a participant’s heart rate is higher after the experiment than before it, the value of hrdecr will be negative. The contribution of this variable is shown in figure 5 below.
Figure 5. Histogram of individual cases of heart rate difference before and after the experiment.
As expected the histogram shows that for 13 out of the 16 participants their heart rate was higher than that recorded at the beginning of the experiment. This demonstrates that road rage does seem have an effect on heart rate.
HOW CAN I TEST THE SIGNIFICANCE OF THIS EFFECT?
Correlation between hrdecr and duration? OR SHALL I NOT BOTHER?
Finally, the further analysis focuses on differences between males and females and their PADS scores. As shown by the ANOVA males spent significantly longer than females verbalising their road rage reactions, thus we can hypothesise that male’s scores on the PADS scale will be significantly higher than females. Figure 6 shows the mean scores on the PADS scale according to gender, and indicates that male’s scores were higher than females. An independent samples t-test has been conducted to test whether these differences were significant.
Figure 6. Mean PADS scores for males and females (higher score indicates a more aggressive driver).
Independent Samples Test
Figure 7. SPSS Output for Independent Samples test on mean PADS score as a function of gender.
Figure 7 indicates that the Levene test is significant thus the unequal variances t-test should be used. Following this it can be seen that PADS score was significantly affected by gender (males scores were higher), (t (1, 10) = 2.7, p <.05).
4. In conclusion the experiment has demonstrated that road rage is more than just simply getting angry at a fellow driver, it effects heart rate, has a significant effect on scores in a propensity to angry driving scale, is significantly affected by gender, and additionally has demonstrated that something as simple as the status of a vehicle can have a significant effect on the type and length of road rage.
It seems that males are more likely to spend longer verbalising their road rage reactions, than females, but interestingly this difference is significant only when the vehicle involved is of a high status. This perhaps suggests something about differences between the male and female personality: especially such components as ego and pride, and is perhaps related to evolutionary psychology, where possessions and assets are very valuable to a male when it comes to competition for mates.
The experiment has also demonstrated some physical effects of road rage, indicated by the increase in heart rate found for participants after the experiment. Although this difference was not significant in this case, it may be due to methodological flaws and/or the fact that this change in heart rate was not sufficient to provide significance, but should still be considered important. Further investigation into the physical effects would be valuable.
The experiment further demonstrated that males became significantly angrier than females following completion of the study, as indicated by higher scores on the PADS scale. This may have implications for real life, in that males may be considered more susceptible to being involved in road rage incidents, and measures could be taken to avoid this.
Overall, this experiment has shown that different people react to road rage in very different ways, males can perhaps be considered more volatile in such situations, particularly when the vehicle involved is of a high status and thus perhaps poses some threat.
