Pitts, R.C., Hughes, C.E. and Williams, D.C. 2019. Transitions from Rich-to-Lean Schedules Increase Attack in a Laboratory Model of Social Aggression in Pigeons: II. Fixed-interval Schedules. Mexican Journal of Behavior Analysis. 45, 2 (Dec. 2019). DOI:https://doi.org/10.5514/rmac.v45.i2.75582.