A passing scent can bring an old scene to mind. But can simply imagining a smell, without actually smelling anything, also lead us to events from our own lives?
Schlintl and colleagues conducted an online experiment in which 296 women aged 18–35 imagined smells or visual scenes. They wanted to know more than which prompted memories in more people: would changing pleasantness and arousal also change the period and vividness of the memories? The paper appeared online in 2022 and in Psychological Research in 2023.
No specific scents were named
Participants were randomly assigned to eight groups and listened to a 90-second audio recording. Instructions combined three dimensions: smell or visual scene, pleasant or unpleasant, and arousing or calming. No actual fragrances or photographs were presented.
A distinctive feature was that no particular flowers, foods, or places were specified. Participants received only a broad direction, such as a pleasant smell, and decided for themselves what to imagine. Even with the same scent, people differ in whether they have experienced it and what memories it evokes.
They then briefly described their mental image and indicated whether it related to an event in their past. If it did, they reported their age at the time, which was categorized as childhood (0–10), adolescence (11–17), or adulthood (18–35). Vividness was rated on a 0–6 scale.
Memory frequency and vividness were different outcomes
Overall, 230 participants, about 78%, reported imagery related to their own experiences. The proportion was 85% in the olfactory-imagery groups and 70% in the visual-imagery groups, a statistically significant difference.
However, this difference mainly emerged when participants imagined unpleasant things. Memories were reported by 85% in the unpleasant-smell conditions and 56% in the unpleasant-visual conditions. In the pleasant conditions, both were about 85%. Olfactory imagery did not outperform visual imagery in every situation.
Vividness, moreover, showed the reverse pattern. The mean score was higher for visual imagery, at 4.18, than for olfactory imagery, at 3.66. The authors also note that the practical importance of a difference of about half a point on a 0–6 scale needs separate consideration. Having imagery arise in more people is not the same as experiencing it vividly.
Pleasant and unpleasant smells led back to different periods
Among participants imagining smells, 20% in the pleasant conditions reported childhood events. In the unpleasant-smell conditions, childhood memories were almost absent.
The comparison matters here. When pleasant smells were compared with pleasant visual scenes, the difference in the proportion of childhood memories was not statistically clear. We cannot conclude that smell is always the best thing to imagine for recalling early life.
In the unpleasant conditions, 60% reported adult memories with olfactory imagery, compared with 37% with visual imagery. Conversely, in the pleasant conditions, adolescent memories were reported by 25% with visual imagery and 10% with olfactory imagery. The period to which thoughts turn may depend on the combination of sensory modality and pleasantness.
In an exploratory analysis in which two psychologists categorized the content, unpleasant olfactory imagery frequently concerned disgust-related events, whereas visual imagery covered a wider range, including sadness, anxiety, and anger. In the pleasant conditions, about 90% in both modalities concerned happiness. The authors also use these emotional differences as a clue to differences in the periods recalled.
People generate cues meaningful to themselves
The authors emphasize the ability to generate personally meaningful cues rather than having researchers present the same predetermined odors to everyone. They suggest that allowing people to choose what to imagine may have made experiences associated with smell more accessible without visual information dominating. This is an explanatory hypothesis, not a mechanism directly measured in the study.
Because no equipment is needed, the method is also convenient for research involving many people in different locations. The authors further mention the potential to draw on pleasant childhood memories as a resource in psychological support or to assist psychotherapy addressing recent disgust-related memories. However, this was not a trial in people requiring treatment, and therapeutic effectiveness was not tested.
Most participants were university students, and all were young adult women. The measurements were self-reports, not checks that the memories were factually accurate. There was also no direct comparison with actually smelling odors, so the study cannot establish that imagination is better than real scents.
Pleasant and unpleasant instructions were reflected in ratings, but, with limited exceptions, instructions intended to alter arousal did not produce the intended differences. Future work needs broader ages and genders and should examine how specifically events are recalled, the richness of their details, and the effort required to remember them.
Summary
Even without smelling anything, freely imagining odors brought imagery linked to personal experiences to many participants. Its occurrence varied with pleasantness, while visual imagery was more vivid.
The study opens a route to generating cues from personal experience rather than delivering the same smell to everyone. Which sense is imagined, and with what feeling? Considering that combination provides a starting point for studying personal memories and exploring future psychological support.
References
Schlintl, C., Zorjan, S., & Schienle, A. (2023). Olfactory imagery as a retrieval method for autobiographical memories. Psychological Research, 87, 862–871. DOI: 10.1007/s00426-022-01701-y / Full text (published online in 2022). Original article: © The Author(s) 2022, CC BY 4.0.
