Will hitchhikers get more rides if they stare at oncoming drivers or if they look away? A 1974 study published in the Journal of Applied Social Psychology
attempted to answer this question:
A field experiment was conducted in which a single male, a single female, or a male-female couple attempted to hitch rides at four different traffic locations, under conditions in which the hitchhikers either stared at or looked away from oncoming drivers...
In the stare conditions, E stared at the driver of the target vehicle and attempted to fixate on the driver's gaze and maintain this gaze as long as possible until the driver either stopped his vehicle or drove on. In the comparison conditions, E looked anywhere else but at the driver. Thus, on some trials E looked in the general direction of the car; on other trials E looked at his feet, the road, the sky, etc. Es were specifically instructed to neither smile nor frown, and to maintain a casual (neither rigid nor slouching) body postural orientation while soliciting rides.
The two hitchhikers were described as, "both 20 years of age and both dressed in bluejeans and dark coats. The male had short, curly blond hair, and the female, straight, shoulder length blond hair. Both could be described as neat, collegiate, attractive in physical appearance, and of an appropriate age to be hitchhiking."
A hitchhiker in Luxembourg - Aug 1977 (source: wiktionary.org)
(not one of the hitchhikers in the study)
Staring is often interpreted as a threat. So the researchers anticipated that staring at oncoming drivers might result in fewer rides. But the opposite turned out to be true. Which is a useful tip to know if you ever need to hitchhike. But what really helped get a lot of rides was being a single female. From the study:
it seems that the effect of attempted eye contact and sex of hitchhikers were such that a staring female got the most rides and a nonstaring male the least, with a staring male and a nonstaring female in between.
Contrary to popular belief and hitchhiking folklore , it was no easier for a male-female couple to hitch a ride than a single male, and a mixed sex couple was less successful at soliciting rides than a single female hitchhiker. Although the generality of this conclusion is limited by the fact that it is based upon results obtained by one male and one female E, it is probably the case that couples are less successful hitching rides because of space limitations in the cars they approach. That is, it is more likely that the driver will have room for one additional passenger than that he will have room for two or more additional passengers in his car.
Incidentally, the experimenters never actually ever got in a car with anyone: "After a motorist stopped to pick up one of the hitchhikers, he was politely thanked and given a printed description of the nature of the experiment. No driver expressed any discomfort when he learned that the hitchhiker did not actually want a ride."