It also produces a negativity bias, another feature of anhedonia. To simulate adulthood, we “froze” agents’ temporal representations and then placed them in an environment with predictably timed rewards. ELU agents’ showed larger prediction errors when reward was omitted than when received. (8/10)

It diminishes reward expectations at the time points just before reward is most likely to occur. Let’s say these Pavlovian values were transferred to instrumental actions — this would produce reduced motivation to pursue rewards, one characterizing feature of anhedonia. (7/10)

Agents developed temporal representations that mimicked the statistics of their environment. Early Life Unpredictability agents (ELU) ended up relying on less precise representations, which temporally “smeared” their reward expectations. This temporal smearing has important consequences. (6/10)

We had two groups of agents who experienced different degrees of unpredictability in reward timing. By manipulating unpredictability in the *timing* rather than *presence* of reward, we could isolate the impact of unpredictability from environment richness. (5/10)

Under this variant of the TD model, time intervals are represented with a weighted set of temporal receptive fields, microstimuli, that vary in their precision or “spread.” The weights are adjusted with experience to make better predictions of if and when reward will occur following the cue. (4/10)