The results of a study published in the October issue of Accident Analysis & Prevention suggest that people who text and drive may be more impulsive than their peers.

Using students’ discount rates as a behavioral measure of impulsivity, Hayashi, Russo and Wirth examined whether students who text while driving have higher discount rates than those who do not.

The behavioral economic concept of discounting holds that people make impulsive choices if they prefer smaller immediate rewards instead of larger delayed rewards (Ainslie and Haslam, 1992; Thaler, 1981). The discounting of future outcomes has been linked to a number of impulsive behaviors such as the consumption of unhealthy food (Epstein, 2010) and instances of substance dependence (e.g. MacKillop et al., 2011), whereby short-term utility (e.g. pleasure or satiation) overrides negative long-term effects.

Hayashi et al expected that students who text while driving would assign a greater subjective value to texting while driving (an immediate reward) than to texting when not driving, resulting in a higher discount rate.

The significant safety risk posed by texting while driving underscores the importance of research in this area. In the US, the National Safety Council estimated that texting while driving is a factor in up to 14% of motor vehicle crashes. Hayashi comments, “Understanding what motivates texting while driving is a basic prerequisite for designing and evaluating effective countermeasures for the problem.”

The sample consisted of 92 students enrolled in introductory psychology courses at a university in the Northeastern United States. Self-reports of texting while driving are particularly high among US college students, with 74-92% indicating that they text while they are behind the wheel (Atchley et al., 2011; Cook and Jones, 2011; Harrison, 2011).

Students were initially screened for their texting while driving behaviors (Atchley et al., 2011). Based on their scores, a texting while driving and a non-texting while driving group were defined, matched on gender, years of higher education, and years of driving experience and comprised of a subsample of the larger group. Students completed a demographic survey and a delay-discounting task, and they reported the frequency with which they texted while driving and the danger they perceived from reading, replying, and initiating a text message while driving.

In the delay-discounting task students were asked to make a series of choices between a smaller, more immediate, reward or a larger, delayed reward. Both rewards were presented in terms of (hypothetical) monetary amounts. The students chose between a constant, larger reward to be received later on and an increasing, albeit smaller reward to be received immediately.

The point (monetary amount) where they just preferred the smaller immediate reward to the larger delayed reward represented their point of indifference whereby the subjective value of the smaller, more immediate reward is equivalent to the larger, delayed reward. Students completed this sequence of trade-offs over seven different delay intervals ranging from 1 week to 10 years.

Confirming their hypothesis, Hayashi and colleagues found that students with higher discount rates (i.e. smaller but immediate hypothetical monetary rewards were preferred over larger, delayed rewards) were indeed more likely to text while driving.

“The results indicate that behavioral measures of reward preferences for immediate versus delayed rewards may be useful for identifying drivers who are at increased risk of texting while driving. The results also indicate that impulsive decision-making, as characterized by an individual’s tendency to prefer immediate rewards, may be the behavioral/cognitive process underlying texting while driving.”

In identifying potential interventions, it may be useful to look towards strategies used to overcome other impulsivity-related behaviors. Among the possible approaches which have been empirically validated in other contexts are deposit contracts and contingent rewarding.

Deposit contracts involve putting aside a predetermined amount of money which is forgone if the person fails to follow through on the target behavior (e.g. not texting while driving) (Dallery et al., 2008). This permits the person to pre-commit to the delayed, larger reward over the smaller, more immediate reward. Notably, deposit contracts also leverage the behavioral economic concept of loss aversion whereby the person is loss averse to losing the money they have committed to and are therefore incentivized to follow through on the desirable behavior (not texting while driving).

In contingent rewarding, on the other hand, a positive reinforcement (i.e. reward) is given when desirable behavior is performed (this can be linked back to the notions of operant conditioning initially put forward by Skinner, 1938). A third strategy suggested by Hayashi and colleagues would increase the delay period before which the driver can respond to a text message by imposing some form of response time restriction. Delaying the ability to respond would be expected to diminish to value of replying to the message.

Importantly, Hayashi and colleagues comment “the impulsive decision to text while driving is a complex phenomenon, and there are other factors that influence decision making.” Future research should test these mechanisms in “realistic texting scenarios with rewards that are interpersonal and social in nature” and incorporate environmental factors (e.g. road conditions), for example. Further, it would also be interesting to examine whether people who text while driving also engage in other impulsive behaviors (e.g. unhealthy eating) at higher rates.