Body feedback can influence how we evaluate the world around us

In a study by Jens Forster, college undergrads were asked to evaluate a series of food products that were previously identified as being highly positive (candy bar) or highly negative (beef lung). The names of the food products were presented on a screen in front of participants. By random assignment, 4 objects were presented with vertical movement, 4 with horizontal movement, and 5 with no movement. The movement back and forth or up and down lasted about 18 secs for each object. After the presentation of each object, participants rated the degree to which they liked it and the how much they would like to buy it.

Vertical head movements (nodding) increased liking for the positive stimuli (the foods that people like) compared to the control, whereas it did nothing to how much participants liked the negative foods. On the other hand, horizontal head movements (shaking) decreased liking for negative stimuli (foods that people dislike) compared to the control, but had no effect on positive stimuli. Similar results were obtained for desire to buy product. In other words, the motor action of nodding or shaking amplified existing response tendencies (liking or not liking).

Forster points out that these results are consistent with the so-called motor-compatibility model, which states that behaviors will have a greater affect on responses when the valence of stimuli and the emotional valence linked to the behavior match. In his words, “When the motivational orientation implied by participants’ head movements and target valence are compatible, judgments and behavior became more extreme. When the were incompatible, however, no significant effects of head movements on judgments of well-known products were observed. Mood did not mediate the effects.” (p. 421).

Förster, J. (2004). How body feedback influences consumers’ evaluation of products. Journal of Consumer Psychology, 14(4), 416-426.