The Effects of Expectations on Perception: Experimental Design Issues and Further Evidence

26 Pages Posted: 16 Dec 2007

See all articles by Tyler Williams

Tyler Williams

Federal Reserve Bank of Boston

Date Written: September 13, 2007


Numerous studies have found that top-down processes can affect perceptions. This study examines some of the issues involved in designing field experiments aimed at discovering whether top-down mental processes affect perceptions, and, if so, how the influence takes place. Lee, Frederick, and Ariely (2006) (LFA) attempt to go further by testing whether expectations affect perception directly, by altering how sensory receptors and/or the brain's processing centers interpret a outside stimulus - or indirectly, for example, by changing the amount of attention paid to the outside stimulus. In order to test the robustness of the findings in LFA, this paper reports the results of a field experiment similar to the one analyzed in LFA. The field experiment, designed to address some potential confounding factors in this type of research, confirms that expectations can alter perceptions. However, it also shows that heterogeneity across individuals can play a role in determining the nature of this effect, a finding that complicates the interpretation of results such as those in LFA. To frame the analysis, this paper discusses the difficulties in designing this type of experiment, makes some improvements to existing designs, and suggests some ways of eliminating the confounding influences that remain.

JEL Classification: D83, D84, D87

Suggested Citation

Williams, Tyler, The Effects of Expectations on Perception: Experimental Design Issues and Further Evidence (September 13, 2007). FRB of Boston Working Paper No. 07-14. Available at SSRN: or

Tyler Williams (Contact Author)

Federal Reserve Bank of Boston ( email )

600 Atlantic Avenue
Boston, MA 02210
United States

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