Berger & Pope's lab experiment found trailing subjects increased effort while leading subjects did not slack off, isolating loss aversion from winning-team complacency

The NBA halftime-deficit finding (claim-berger-pope-nba-halftime-deficit-raises-win-probability) is consistent with two different mechanisms: trailing teams could be trying harder (loss aversion), or leading teams could be coasting (complacency) — the field data on win probabilities alone cannot distinguish them, since either would produce the same reversal. Berger & Pope ran a laboratory experiment specifically to separate the two. Participants told they were "slightly behind" an opponent on a competitive task increased effort significantly more than controls or than participants told they were "slightly ahead"; being ahead did not measurably reduce effort relative to the control condition.

The authors read this as evidence against the rival explanation, in their own words: the lab results "cast doubt on the possibility that the winning team simply becomes complacent (as opposed to the losing team exerting more effort)." Because the lab setting removes coaching decisions, referee behavior, and any strategic in-game adjustment — the confounds available in the NBA data — the design targets the individual-effort channel specifically, and locates the effect in the losing side's motivation rather than the winning side's ease.

This is the piece of the paper's argument that upgrades "teams behind at halftime win more than expected" (a pattern) into "loss aversion" (a mechanism) — the field result alone is compatible with several stories; the lab result narrows them. It strengthens the shared reference-point-plus-loss-aversion engine already named in claim-goals-as-reference-points-below-goal-work-harder by ruling out the most obvious alternative explanation for one of the engine's three domains.