Why is the CPT so expensive?
Recently, I was charged with administering an attention evaluation task as part of a research experiment. The test, called a ‘CPT,’ was a very simple computerized task, which could be completed on a standard laptop. I instructed the children being tested to sit comfortably and squarely in front of the laptop screen, with their hand on the space bar. Once the test started, black letters would periodically appear and disappear against a white background on the screen, at different intervals. Every time a letter appeared, the participant had to press down once on the space bar, as soon as they saw it. The only exception was the letter ‘X,’ and when it appeared, the child had to keep from pressing the space bar. This procedure went on for 15 minutes, and the person being tested could not stop the task once they had started the test. For the 10–12 year-old kids I tested that day, the combination of uninteresting visuals and a very simple, repetitive process added up to an excruciatingly boring 15 minutes. Even I found the test to be very uninspiring: the black-on-white display and very simple task seemed to me like a computer program that any professional software developer could create with little effort. Therefore, when I inquired about the price of this software I was very surprised by the answer I received: the laboratory had purchased one example of the unlimited use kit for a hefty 2000$. The flimsy USB key containing the CPT test cost more than the computer it was being used on! My astonishment led me to investigate on what could justify the expensive price tag of the CPT — more than twice the price of a standard intelligence testing kit. Was this test really worth the cost?
The Conners Continuous Performance Test 3rd Edition™ (Conners CPT 3™) is described as “task-oriented computerized assessment of attention-related problems in individuals aged 8 years and older.” (Conners, n.d.) The test can be used in diagnosing Attention-Deficit/Hyperactive Disorder (ADHD) and other similar attention-related neurological conditions. It turns out that from the simple action of pressing on a space bar, 16 different scores can be obtained, observing four different facets of attention problems: inattentiveness, impulsivity, sustained attention, and vigilance. For example, the score of “HRT Standard Deviation (SD),” described as the “response speed consistency” gives useful information on the dimension of inattentiveness, and “commissions” or “incorrect responses to non-targets” (mistakenly pressing the space bar when an ‘X’ appears) relates to impulsivity. (Conners, n.d.) But how do these scores rate on the validity scale? Epstein et al. investigated the issue in their 2003 article “Relations between Continuous Performance Test Performance Measures and ADHD Behaviours.” The authors examined the relationship between CPT variables and phenotypic behaviours in children by administering the Conners CPT and conducting diagnostic interviews for 817 children. The results were good, and they found that “overall performance on (the task) was highly related to all ADHD symptoms across symptom domains.” (Epstein et al., 2003) Therefore, these findings show that the Conners CPT is indeed successful in testing the variables it claims to be assessing, at least for ADHD.
Finally, it seems the CPT is far more complex than it appears to be. The simple black and white space-bar-pressing task analyzes four different facets of attention problems and computes a total of sixteen different scores. Also, according to Epstein et al., it is a very useful test since it truly does evaluate symptoms of ADHD. So, is this test worth its 2000$ price tag? I think I would have to conduct further research in order to be fully convinced. For example, what sets this test apart from the others? However, even though I don’t doubt the expertise of those who conceived the CPT and the years of research that went behind the development of this test, the artist in me still believes it could definitely be improved on the visual level.
Conners, C. (n.d.). Conners CPT 3™. Retrieved March 18, 2016, from http://www.mhs.com/product.aspx?gr=edu
Epstein, J. N., Erkanli, A., Conners, C., Klaric, J., Costello, J. E., & Angold, A. (2003). Relations Between Continuous Performance Test Performance Measures and ADHD Behaviours [Abstract]. Journal of Abnormal Child Psychology, 31(5), 543–554. Retrieved March 13, 2016.