|
| Int'l Paper Session - EAB II |
| Monday, May 30, 2005 |
| 3:00 PM–3:50 PM |
| Private Dining Room 3 (3rd floor) |
| Area: EAB |
| Chair: Mark E. Berg (University of Canterbury, New Zealand) |
| |
| A Lifespan Investigation of the Delay Discounting of Monetary Rewards |
| Domain: Basic Research |
| LOUISE A. MCHUGH (University of Wales, Swansea), Carla Thompson (University of Wales, Swansea), Robert Whelan (APU, Cambridge, UK) |
| |
| Abstract: Temporal discounting refers to the weakening of consequence effects due to delay. The aim of the current study was to investigate temporal discounting across three age groups: 12, 16, and 20-yr olds. In the current study, the delay of the larger later reward and the amount of the smaller sooner reward were varied. Results showed that all three age groups demonstrated temporal discounting and that the level of delay discounting, the k value, was inversely related to age. Thus, the results from the current study demonstrated developmental trends that reflect previous findings in this area, such as those described by Green, Fry and Myerson (1994). The current study is novel in that an automated procedure was employed, and the addition of the 16-yr old group represents an extension of Green et al.’s research. |
| |
| Effects of Initial-Link Duration on Molecular Measures of Initial- and Terminal-Link Performance |
| Domain: Basic Research |
| MARK E. BERG (University of Canterbury, New Zealand), Randolph C. Grace (University of Canterbury, New Zealand) |
| |
| Abstract: Four pigeons responded in a concurrent-chains/peak procedure in which the terminal links were FI 8 s and FI 16 s and the initial links were either short (VI 8 s) or long (VI 24 s) across conditions. The terminal links were equivalent to trials in a peak procedure (Roberts, 1981): On 75% of the trials, food was available after the FI value had elapsed, but on the remaining 25% the terminal link lasted for 48 s and ended without food delivery. We recorded both molar and molecular (i.e., single trial) measures of performance in both the initial- and terminal links. Molar analyses showed that preference for the FI 8 s was less extreme with long initial links, consistent with many prior studies (e.g., Fantino, 1969). Measures of single-trial peak performance (e.g., start time, stop time, peak response rate) did not vary with initial-link duration. Molecular analyses showed that the attenuation of preference in the long initial-link conditions was primarily due to an increase in visit duration to the lean alternative. Regression analyses showed that measures of initial-link performance contributed unique variance, above and beyond terminal-link delay, to the prediction of stop times. Overall, these results show that trial-by-trial variation in temporal measures of initial- and terminal-link performance are correlated, suggesting that an integrated account of choice and timing may be justified. |
| |
|
| |