Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Earned infusions at each nicotine dose during acquisition (Phase 1) and reduction (Phase 3).
Earned infusions over the last three sessions of acquisition (Phase 1, filled circles) and reduction (Phase 3, filled squares).Significant increase in infusions earned for from Phase 1 to Phase 3 (p<0.0125), and significant nicotine × phase interaction (p<0.017) denoted by *. Bars represent standard errors
