If your attention is elsewhere you can miss something right in front of your eyes – a phenomenon that’s been dubbed ‘inattentional blindness’. For example, witnesses confronted by an armed attacker sometimes fail to remember anything else about the assailant apart from their weapon, so preoccupied were they by the knife or gun. Now Seema Clifasefi and colleagues report that just one stiff drink can exaggerate inattentional blindness, a finding they argue justifies the setting of a lower legal alcohol driving limit.
Forty-seven students watched a short video clip of two teams passing a basketball between their respective team members. The participants’ task was to count the number of passes made by one of the teams. During the clip, a woman in a gorilla suit runs between the players and beats her chest. Crucially, when asked afterwards, only 18 per cent of the students given a drink of vodka and tonic said they’d noticed the woman, compared with 46 per cent of the students given a drink of plain tonic water.
Alcohol clearly exaggerated the inattentional blindness that was also experienced by many of the sober students.
This wasn’t a placebo effect – half the students given plain tonic water were told they had been given vodka, and yet 42 per cent of them noticed the gorilla woman. By contrast, half the students given vodka were told they’d been given tonic water, and yet only 18 per cent of them noticed the gorilla. The alcohol seems to have had a direct effect on the participants’ cognition.
“Even at only half the legal driving limit in the US, our subjects were at significantly increased risk of failing to notice an unexpected object compared with their sober counterparts. In light of this result, perhaps lawmakers should reconsider the level of intoxication deemed legal to operate a vehicle”, the researchers concluded.
Clifasefi, S.L., Takarangi, M.K.T. & Bergman, J.S. (2006). Blink drunk: The effects of alcohol on inattentional blindness. Applied Cognitive Psychology, 20, 697-704.