Initial meta-analytic evidence for an odour-evoked context-dependent episodic memory effect

The environmental context in which items are visually perceived has been suggested to influence how well they are subsequently remembered. One context that has been proposed to be relevant to memory performance is environmental odours. Some previous research has suggested that having the same odour present during encoding and testing boosts performance compared to different odours being present at each point - a odour-evoked context-dependent memory (OCDM) effect. There is, however, some inconsistency in this literature. We therefore conducted a quantitative meta-analysis in order to produce an estimate of integrated effect across studies. This analysis suggests that a positive OCDM effect may exist (estimated Hedge’s g = 0.44 [95% CI = 0.16 0.72]). Further analysis suggested that the outcome may be modulated by the type of memory probe (recall vs recognition) and stimulus (text vs picture) used. These results should be treated with caution though, as the studies included were substantially underpowered to reliably detect plausibly sized effects. These results identify potential methodological modulators of the OCDM effect. They also point to there being merit in conducting large, pre-registered studies on this effect to confirm its existence and to obtain accurate estimates of its size.