In much the same way that an animal freezes or slows at the sight of a predator, humans are automatically slowed down when they see or read something unpleasant.
That’s according to Benjamin Wilkowski and Michael Robinson at North Dakota State University. They presented 38 students with a series of pictures that were either positive (e.g. a passionate couple), negative (e.g. a gun placed to someone’s head) or neutral (e.g. a basket). After the presentation of each picture, the students had to identify whether the screen was showing one or two dots, and then press the appropriate number on a button box as quickly as possible. They had to do this three times after each picture to ensure any effects weren’t simply due to difficulty disengaging their attention from the last picture.
The researchers found that, on average, the students’ responses were significantly slower after they’d just seen a negative picture than if they’d seen a neutral picture (475 ms average response time vs. 423 ms). A similar slowing effect was found after the presentation of violent words (e.g. murder) compared with neutral words (e.g. walk). In contrast, there was no difference in their response times after viewing positive pictures or words compared with after viewing neutral pictures/words.
A final experiment featuring a joystick, showed negative words slowed the speed with which participants moved the joystick up and down, but did not slow the actual onset of their movement. The researchers said this makes evolutionary sense because it means that in the presence of danger we still decide which movement to make quickly, but “that avoidance behaviours, once initiated, are performed in a stealthful and thus less detectable manner”.
Wilkowski, B.M. & Robinson, M.D. (2006). Stopping dead in one’s tracks: Motor inhibition following incidental evaluations. Journal of Experimental Social Psychology, 42, 479-490.
Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.