1. Editorial

   EditorialNotes Pages: 215 - 215

2. Timing with opportunity cost: Concurrent schedules of reinforcement improve peak timing

   • Federico Sanabria
   • Eric A. Thrailkill
   • Peter R. Killeen

   OriginalPaper Pages: 217 - 229

3. Representations of single and compound stimuli in negative and positive patterning

   • Justin A. Harris
   • Saba Gharaei
   • Clinton A. Moore

   OriginalPaper Pages: 230 - 245

4. The effects of rapid eye movement sleep deprivation and recovery on spatial reference memory of young rats

   • Shenghui Li
   • Ying Tian
   • Xiaoming Shen

   OriginalPaper Pages: 246 - 253

5. Overshadowing and CS duration: counteraction and a reexamination of the role of within-compound associations in cue competition

   • Heather T. Sissons
   • Gonzalo P. Urcelay
   • Ralph R. Miller

   OriginalPaper Pages: 254 - 268

6. Social effects on spatial choice in the radial arm maze

   • Michael F. Brown
   • Toni-Moi N. Prince
   • Karen E. Doyle

   OriginalPaper Pages: 269 - 280

7. Reward contrast in delay and probability discounting

   • Zhijie Dai
   • Randolph C. Grace
   • Simon Kemp

   OriginalPaper Pages: 281 - 288