The Point of No Return in Snack Consumption

This paper investigates the psychological "point of no return" in discretionary snack consumption, the threshold beyond which cessation becomes cognitively costly and continuation becomes the default. Through a series of laboratory experiments (total n=840), we identify this threshold with precision and examine its underlying mechanisms.

In our primary paradigm, subjects were provided with transparent bags of snack foods (chips, crackers, candy) and asked to consume as much or as little as they wished while engaged in a distraction task (watching a video). Unknown to subjects, consumption was measured through bag weight at 10-second intervals. Post-consumption, subjects reported their experience of decision-making, including moments of considering stopping and moments of experiencing consumption as "automatic."

Results reveal a consistent threshold at approximately 62% consumption (95% CI: 59-65%). Prior to this point, subjects report active decision-making about continuation; after this point, they report consumption as "just happening" without deliberate choice. Neuroimaging data from a subset of subjects (n=60) shows corresponding shifts in prefrontal activity, with decreased dlPFC engagement post-threshold consistent with reduced deliberative processing.

We propose the "completion momentum" model to explain this phenomenon: as consumption progresses, the cognitive representation of the task shifts from "eating some chips" to "finishing the chips," and the reference point for effort shifts accordingly. Stopping before 62% requires only abandoning an ongoing activity; stopping after 62% requires actively resisting the pull of an almost-completed goal.

Practical implications for packaging design, portion control, and public health interventions are discussed. We note that single-serving packages that contain approximately 60% of typical consumption volume may inadvertently position consumers at the threshold, making overconsumption more likely when multiple packages are available.