When you are absorbed in a screen, do you perceive the aroma of nearby food in the usual way? How intense an odor feels may depend not only on how much of its ingredients reaches the nose, but also on what you are attending to at that moment.
In 2021, Stephan Schadll and colleagues asked 30 healthy adults to play Tetris to investigate whether game difficulty changes odor-intensity ratings. Behind this was a question about how attending to television or games while eating relates to eating behavior. The researchers first examined an earlier step: how odors are perceived.
The same people play easy and difficult Tetris
The participants were 30 adults aged 18–32 who met criteria including an olfactory test. Banana and orange were used as food odors, leather and a wood-like scent as non-food odors, and odorless water as a control. A pilot study with 13 other people found no clear differences in intensity among the four odors.
Difficulty was varied by changing how fast the blocks fell. In the easy condition, a block took 0.47 seconds to fall one cell; in the difficult condition, it took 0.1 seconds. Every participant experienced both conditions, completing 40 rounds in total with odor and difficulty order randomized.
Each round lasted 56 seconds. Participants played only the game in the first half, while during the second 28 seconds a device intermittently delivered odor to both nostrils at a constant airflow. After every round, they rated odor intensity and game difficulty separately from 1 to 10.
In the difficult condition, participants cleared fewer rows, rated the game as harder, and showed a greater skin-conductance response associated with sweating. Thus, differences in workload were checked using behavior and bodily responses, not just game settings. The comparison was between two conditions of playing Tetris, not between playing and not playing.
Food-odor ratings fell from an average of 6.29 to 5.87
In the analysis combining all four odors, intensity ratings were lower when the game was harder. For food odors alone, the mean rating fell from 6.29 in the easy condition to 5.87 in the difficult condition, a statistically clear difference. This was an average decrease of 0.42 on a ten-point scale, not a change so large that odors became imperceptible.
Non-food odor ratings also fell, from an average of 5.47 to 5.24, but that comparison alone did not show a clear difference. There was also no statistical evidence that difficulty affected food and non-food odors differently. It is therefore not possible to conclude either that only food odors were affected or that equally sized effects were established for both categories.
There was no difficulty-related difference in ratings for the odorless control. The study also asked about intensity, not how pleasant or familiar the odors were.
Does using attention elsewhere leave less capacity for scent?
The authors suggest that devoting more attention to a difficult game may leave less attention available for odors. A distinctive feature of the study is that odor ratings changed during an everyday game, rather than only during tasks such as remembering strings of characters.
However, attention alone was not established as the explanation. Breathing was not recorded, leaving open the possibility that difficult moments changed breathing and therefore how much odor entered the nose. Brain activity was not measured either. Skin responses were used to check game-related workload, not as an objective measurement of perceived odor intensity itself.
There was also a difference in delivery: odors were presented from jars in the pilot study and through a device in the main experiment. With only two food and two non-food odors, it is not known whether the same changes occur for every scent, including foods and perfumes.
Could this help explain distracted eating?
The authors focused on smell as an important component of food flavor. They propose that if games or television draw attention away and make aromas seem weaker, the overall flavor of a meal might also weaken, potentially contributing to increased food intake.
However, participants did not eat during this experiment, and neither food intake nor food choices were measured. The link between lower odor ratings and actual overeating still needs experimental testing.
Based on this idea, the authors suggested limiting television or games during meals. This experiment did not establish that doing so reduces food intake or improves health, however. The next step is to measure perceived flavor and eating behavior together with real food or in settings that combine multiple senses.
Summary
Even when the same people received the same odors, overall intensity ratings were lower during difficult Tetris. The mean decrease was clear for food odors, showing that the experience of scent cannot be separated from other activities taking place at the same time.
These results offer a starting point for considering the hypothesis that distracted eating changes how flavor is perceived. How does odor perception connect to how much people eat? Testing that link should make the mechanisms connecting attention during meals with eating behavior more concrete.
References
Schadll, S., Rodriguez-Raecke, R., Heim, L., & Freiherr, J. (2021). Playing Tetris Lets You Rate Odors as Less Intense. Frontiers in Psychology, 12, 657188. DOI: 10.3389/fpsyg.2021.657188 / Full original article.
Original article license: CC BY 4.0. © 2021 Schadll, Rodriguez-Raecke, Heim and Freiherr.
