1. With Age Comes Wisdom: Age-Based Differences on Choice Dependent and Choice Independent Decision-Making Tasks Darrell A. Worthy 1, Marissa A. Gorlick 2, Jennifer L. Pacheco 2, David M. Schnyer 2, & W. Todd Maddox 2 1. Texas A&M University 2. University of Texas at Austin Introduction Choice-Independent Discussion 1. Marschner, A., Mell, T., Wartenburger, I., Villringer, A., Reischies, F.M., Heekeren, H.R., (2005). Reward-based decision-making and aging. Brain Research Bulletin, 67, 382-390. 2. Mell, T. Heekeren, H.R., Marschner, A., Wartenburger, I., Villringer, A., & Reicschies, F.M., (2005). Effect of aging on stimulus- reward association learning. Neuropsychologia, 43, 554-563. 3 Cook, I.A., Bookheimer, S.Y., Mickes, L., Leuchter, A.F., Kumar, A. (2007) Aging and brain activation with working memory tasks: an fMRI study of connectivity. International Journal of Geriatric Psychiatry, 22, 332-342. 4. Park, D.C., & Reuter- Lorenz, P. (2009). The adaptive brain: Aging and neurocognitive scaffolding. Annual Review of Psychology, 60, 173-196. 5. Otto, A. R., Gureckis, T. M., Markman, A. B., & Love, B. C. (2009). Navigating through Abstract Decision Spaces: Evaluating the Role of State Generalization in a Dynamic Decision- Making Task. Psychonomic Bulletin & Review, 16, 957-963. 6. Glascher, J., Daw, N., Dayan, P., O’Doherty, J. P. (2010). States versus rewards: Dissociable neural prediction error signals underlying model-based and model-free reinforcement learning. Neuron, 66, 585-595. http://worthylab.tamu.edu/Publications worthyda@tamu.edu Supported by NIMH grant MH077708 to WTM and a supplement to NIMH grant MH077708 to DAW.worthyda@tamu.edu Results * * * Choice-Independent Older and younger adults must both regularly make numerous important decisions. One common variable in decision-making situations is whether rewards are dependent or independent of previous choices. Many previous studies have examined how aging affects decision-making in choice independent situations; 1,2 very few have examined choice-dependent decision-making. Several brain regions implicated in decision- making have also been shown to be susceptible to age-related deterioration. 1,2 Older adults may engage a broader network of frontal regions to compensate for reduced activity in striatal-cortical networks. 3 This may enhance their ability to make choice- dependent decisions relative to younger adults. Chose from one of four decks of cards on each trial. Gained 1-10 points on each of 80 trials Tried to earn as many points as possible. Reward were based on the trial number Younger adults earned significantly more points on the task. Results Choice-Dependent These results suggest a qualitative difference in how younger and older adults make decisions. Younger adults – better when rewards are choice- independent. - May focus less on identifying the underlying structure of the environment – decision-making is more model-free 6 Older adults – better when rewards are choice-dependent -may focus on identifying the underlying structure of rewards in the environment – decision-making is model-based Model-free – striatally-mediated Model-based – frontally mediated Results support the neural scaffolding theory of aging. Older adults may recruit a broader area of frontal regions to compensate for age-related declines. 28 healthy older adults (60-84 yrs.) & 28 younger adults (18-23 yrs.) participated. Choice-Dependent Used the Martian-Oxygen Task 5 to examine how age affects choice-dependent decision-making. 52 health older adults (60-82 yrs.) and 51 younger adults (18-26 yrs) participated Participants had to decide which ‘oxygen extraction system’ led to the greatest cumulative oxygen collection. In these tasks the rewards were dependent on the number of Increasing options selected over the previous ten trials. The Decreasing option gave a higher reward on each trial, but decreased the rewards for both options on future trials. Increasing-Optimal Task Repeatedly selecting the Increasing option led to a reward of 80 points; repeatedly selecting the Decreasing option led to a reward of only 40 points, despite giving a higher reward on any given trial. Decreasing-Optimal Task The long-term gain from selecting the increasing option is not greater than the short-term gain from selecting the decreasing option. Participants had to discover the underlying choice- dependent nature of the reward structure to decide whether the Increasing or Decreasing option is the better choice. Older adults selected the Increasing option more than younger adults in the Increasing-optimal task -Less than younger adults in the Decreasing-optimal task Proportion of Increasing options were not statistically different between task for younger adults. Older adults earned more points on both choice- dependent tasks.