Target-selective tilt aftereffect during texture learning

In texture learning, observers are presented with repeated stimulations, resulting in within-day threshold elevation, as well as between day threshold reductions. Within-day deteriorations were shown to be location and orientation specific (Mednick et. al., 2002; Ofen et al., 2007). Accordingly, the declined performance was suggested to reflect sensory adaptation. Here we test whether extensive training produces adaptation dependent tilt after-effects (TAE). Six observers were trained for 5 days on the texture discrimination task (Karni & Sagi, 1991), 800-1000 trials/day. The target (40ms) was composed of 3 lines of 22.5o orientation, stacked vertically or horizontally (2AFC task), embedded in a background of -22.5o lines. The target was followed by a variable blank interval and a mask (100ms). Multiple tests of perceived vertical (PV) were carried out prior and after each daily session to evaluate TAE at four locations, corresponding to: a target line, +22.5o on all trials (T+); both target and background lines, balanced, either +22.5o or -22.5o (T0); and the two background locations, near (BN) and far from the target (BF). Results showed learning across days, with within-day deterioration that varied across days. There was a significant TAE immediately following TDT training at both target's locations, at T+ (-1.6°±0.3, mean±SEM; p< 0.01) and, more surprisingly, at T0 (-0.8°±0.2; p=0.03) but not at background locations (BN, 0.3°±0.3; BF, 0.3°±0.1). The persistence of the TAE varied across days, as indicated by successive PV tests; decaying faster at location T+ (p=0.02), while persisting longer at location T0 (p=0.02). Here we show that texture training induces a localized target-selective TAE, which in return has a training-dependent component. The absence of background TAE and the target-biased TAE at the balanced location indicate that aftereffects are not determined by stimulus statistics, but rather by experience-dependent task-relevance. This supports mutual interactions between sensory adaptation and perceptual learning. Meeting abstract presented at VSS 2015.