Linear mixed-effects modeling (SPSS, version 20.0; IBM Corporation) tested session effects, including age, years of smoking, FTND, IQ, and mean relative head motion as covariates. The relationship between changes of subjective withdrawal and craving and changes of the RAI (smoking vs abstinence states) was investigated using the following regression model: ΔYa−s=β0+β1Δma−s+β2⋅age+β3⋅SmokingYear+β4⋅FTND+β5⋅IQ+β6⋅Δmotiona−s+ε where ΔYa − s is the arithmetic difference of the Minnesota Nicotine Withdrawal Scale withdrawal score or the brief QSU score between the abstinent and smoking states, and Δma − s is the difference of the RAI between the 2 states.
