An ambient coffee-like scent improved performance on an analytical reasoning task because it created higher performance expectations. Kind of placebo effect.

The impact of coffee-like scent on expectations and performance. Adriana Madzharo, Ning Ye, Maureen Morrin, Lauren Block. Journal of Environmental Psychology, https://doi.org/10.1016/j.jenvp.2018.04.001

Highlights
•    An ambient coffee-like scent improved performance on an analytical reasoning task.
•    The scent created higher performance expectations.
•    Expectations about alertness are also associated with the scent.
•    An ambient coffee-like scent had a placebo effect on behavior.

ABSTRACT: The present research explores the effect of an ambient coffee-like scent (versus no scent) on expectations regarding performance on an analytical reasoning task as well as on actual performance. We show that people in a coffee-scented (versus unscented) environment perform better on an analytical reasoning task due to heightened performance expectations (Study 1). We further show that people expect that being in a coffee-scented environment will increase their performance because they expect it will increase their physiological arousal level (Study 2). Our results thus demonstrate that a coffee-like scent (which actually contains no caffeine) can elicit a placebo effect.

Keywords: olfaction; performance; coffee-like scent; placebo effects