'A good IQ test not only measures correct or incorrect, it also measures how fast?'

Psychologist Dylan Molenaar awarded Veni grant for research into response times

25 August 2015

Intelligence is fairly easy to measure by means of a performance or IQ test. One significant variable is not included in the result, however: the response time. Wrongly so, believes psychologist Dylan Molenaar. He has been awarded a Veni grant for the development of statistic models that incorporate the response times.

'As a student, I obviously learned about tests and models that measure intelligence. The question that always fascinated me even then however was, what do we do with the information on response times? As a PhD student I subsequently conducted research into response times. Primarily delving into existing literature on the subject, I discovered that very little relevant research had actually been conducted. 

Which process produces which score?

'The response time is usually measured, but is subsequently viewed as indirect information.' A great shame, in Molenaar's opinion, as he believes there is a great deal to learn in this area. 'The response time provides information about the differences between and in people. Which questions can you answer straight from memory, e.g. what is four times eight, and for which questions do you have to count, calculate or guess the answers? At present, the question is often, what exactly are we measuring? I want to develop statistic models that will ensure we know which process produces which score?

Results will become more reliable

Molenaar does not expect the research results to lead to entirely different test results, but he does expect them to become more reliable. 'The present test might show you to have an IQ of 130 with a five-point error of margin either way. Incorporating the response speed could lead to a score of 130 with a 2-point error of margin either way.'

Important to science, the business world and teaching

The psychologist believes that his research will initially be important in terms of fundamental knowledge of response speed and the underlying processes, but thinks it could also have significant practical implications. 'It would be wonderful if the performance tests commonly conducted for assessments in the business world were to incorporate response speed. Teaching staff would also benefit; they could give far more specific feedback to different items in a test.'

Published by  Faculty of Social and Behavioural Sciences