Sunday, 8 September 2013

Are we Hares or Tortoises? Examining the Speed-Accuracy Tradeoff

New staff member Dr Don van Ravenzwaaij talks about his recent research:
In everyday life, we are constantly confronted with situations that require a quick and accurate action or decision. Examples include mundane tasks such as doing the dishes (we do not want to break china, but we also do not want to spend the next hour polishing), but also more serious activities, such as performing a test. For these actions, there exists a tradeoff, such that more speed comes at the expense of more errors. This phenomenon is called the speed-accuracy tradeoff.

In psychology, we study the speed-accuracy tradeoff by having participants repeatedly make a decision between two alternatives as quickly and accurately as possible. Conclusions from the data of these tasks are often based on the mean response time and the percentage of correct responses. These measures, however, do not speak directly to underlying psychological processes.

In order to draw conclusions about these unobserved processes, one should use a mathematical process model, such as the drift diffusion model (DDM; see Figure 1). The DDM decomposes response time distributions into their constituent components, such as the speed of information processing, response caution, and time needed for non-decision processes (i.e., response execution).

Figure 1
In my research, I have used the DDM to demonstrate that the effects of alcohol on response times lead to a deterioration in cognitive performance before motor processes are impaired (van Ravenzwaaij, Dutilh, & Wagenmakers, 2012). I have applied the DDM to the Implicit Association Test, designed to measure racial prejudice, and concluded that the effect measured by this test is in fact not driven by racial prejudice, but by ingroup/outgroup status (van Ravenzwaaij, van der Maas, & Wagenmakers, 2011, see Psychology Today for coverage in the popular media). Using the DDM, I have also demonstrated that playing action video games does not lead to faster information processing, despite claims to the contrary in the popular media (van Ravenzwaaij et al., 2013).

For more information on these and other research projects, please visit my website: or contact me at