Christoff et al. (2018) — Mind-Wandering as a Scientific Concept: Cutting through the Definitional Haze
A theoretical Letter in Trends in Cognitive Sciences, published with its rebuttal (Seli et al., The Family-Resemblances Framework for Mind-Wandering Remains Well Clad, same issue). The pair is the compact primary statement of a dispute the wiki had been leaning on without ever recording: what, if anything, makes a thought a case of mind-wandering.
It is here for one reason. The wiki’s body-wandering construct — the embodied slice of the resting stream of thought, from Banellis et al. (2026) — is a kind of mind-wandering, and its own concept page notes that “the wiki had no page for mind-wandering or spontaneous thought at all” when it was written. Whether body-wandering counts as mind-wandering at all depends on which side of this debate one stands on, because body-wandering can be either free-drifting or the ruminative, constrained fixation on a bodily symptom that the two frameworks classify oppositely.
The disagreement, stripped down
Everyone in the exchange agrees the term has been overstretched, and agrees that membership in the category is graded rather than all-or-none. The entire fight is over one question:
Is there a feature a thought must have to be mind-wandering — or not?
Christoff et al. (dynamic framework): yes. The defining feature is relatively unconstrained dynamics — thoughts that arise and move freely, not held on course by either deliberate goals or automatic (e.g. affective, perseverative) constraints. This is a definitional approach: it draws a boundary and accepts that some things previously called mind-wandering fall outside it.
Seli et al. (family-resemblances): no. Mind-wandering is a cluster concept — a family whose members share overlapping resemblances with no single common thread, membership probabilistic and multidimensional, some exemplars more prototypical than others. No feature is privileged over any other.
The test case that makes it concrete
The two views are distinguishable exactly where they classify the same thoughts differently. Christoff et al.’s own table:
| type of thought | dynamic framework | family-resemblances |
|---|---|---|
| perseverative task-unrelated thoughts (rumination) | not MW | is MW |
| purposeful thoughts about holiday activities (task-unrelated) | not MW | is MW |
| deliberately planning a dinner date in calculus class | not MW | is MW |
| letting one’s mind wander by a lake | is MW | is MW |
The dynamic framework excludes the top three because they are constrained — by perseveration or by deliberate goals. This is the stake for a wiki that cares about the body: ruminating on a symptom and idly noticing the breath are both “thought about the body,” but only the second is mind-wandering under the dynamic view. That distinction is the same one the wiki keeps meeting from the clinical side — elaborative vs sensory reactivity, decentering, cognitive-reactivity — where what harms is not the bodily content but whether thought is locked-on and elaborating.
Each side’s strongest move
Christoff et al.’s sharpest argument is the dissolution worry: family-resemblances makes the boundary so porous that “as long as at least one researcher refers to a type of thought as ‘mind-wandering’, this type of thought would become part of the family,” until the concept is synonymous with thought and the field loses any focus that separates it from cognition in general — “the mind-wandering emperor really has no clothes.”
Seli et al.’s sharpest reply is the false-dichotomy charge: the choice is not “exclusive definition or nothing.” A cluster concept is a third, scientific option with real structure (graded, probabilistic, prototype-based), and — turning the knife — the dynamic framework’s own criterion, “relative lack of constraint,” is itself vague enough that it fails to cleanly separate mind-wandering from other thought. And empirically, the field has flourished without consensus, so the existential threat is overstated.
What it does to the wiki
It supplies the definition the body-wandering page was missing, and it supplies it as a live dispute rather than a settled fact — which is the honest state of the field. The wiki now records mind-wandering as a concept and the definitional split as a debate.
It contradicts nothing. No wiki page had committed to a definition of mind-wandering; Banellis et al. and Weng et al.’s EMBODY both sample or decode mind-wandering operationally without adjudicating what it essentially is. This Letter names the assumption underneath both.
It plants one flag worth keeping. If the dynamic framework is right, then the empirical question “is body-wandering protective or harmful?” (is-more-interoceptive-awareness-better) may be mis-posed whenever body-wandering blends free drift toward the body with constrained fixation on it — two states this debate says should not share a label. Banellis et al.’s single-probe MDES cannot separate them; the debate says they must be separated.
Provenance
Two Letters in the Correspondence section of Trends in Cognitive Sciences 22(11), November 2018. Christoff (UBC Psychology / Centre for Brain Health) is the senior voice of the dynamic-framework camp; the reply is led by Paul Seli (then Harvard) with Kane, Metzinger, Smallwood, Schacter, Maillet, Schooler and Smilek — Jonathan Smallwood among them, the same MDES architect whose framework Banellis et al. later extend to the body, which places the wiki’s body-wandering instrument on the family-resemblances side of its own author lineage. The file also contains, on its first two pages, an unrelated Continuous Flash Suppression correspondence (Sklar, Deouell & Hassin) that is not ingested.