Gorilla watching: Effects of exposure and expectations on inattentional blindness

Inattentional blindness (IB) occurs when an individual fails to notice an unexpected object because their attention is engaged by another task. Most research has excluded participants with IB knowledge on the belief that any knowledge of IB would invalidate experiments by causing participants to "expect the unexpected". Previous research has shown that expectations can significantly influence IB rates, specifically through determining attentional set. We conducted a series of experiments to determine whether knowledge of and exposure to IB research had any effect on expectations and rates of IB. Experiment 1 compared participants with either little or no preexisting knowledge of IB and found that IB knowledge did not predict experimental rates of IB. Experiment 2 compared first year psychology students with moderate IB knowledge to later-year students with high IB knowledge. Again, knowledge was not a significant predictor of IB rates. Experiment 3 manipulated IB knowledge, with half the participants given detailed information on IB. High knowledge participants were significantly more likely to notice the unexpected stimulus, but primary task accuracy was significantly lower for noticers compared to nonnoticers, suggesting that noticers may have adopted a dual task strategy and been "watching" for the unexpected stimulus. Overall these results suggest that preexisting IB knowledge only affects rates of IB if it allows participants to form specific and accurate expectations about the experiment