Perceptual learning modifies serial dependence effects in orientation and facial expression perception

Serial dependence refers to an attractive bias in perception and cognition toward recent past experiences. Although it is stable within individuals, whether perceptual learning can modify this stability remains unclear. Here we investigated the modifiability of serial dependence across low-level and high-level visual processings, using orientation grating (Experiment 1) and facial expression (Experiment 2) respectively. Participants in the experimental group underwent five consecutive days of intensive perceptual training, while participants in the control group did not. All participants performed a serial dependence test and a discrimination test before and after training in the two experiments. The results showed that participants in the experimental group improved discrimination abilities and reduced the magnitude of the serial dependence effect after training for both low-level and high-level stimuli, whereas participants in the control group did not show these effects. This research provides direct evidence that perceptual learning can modify serial dependence across different levels of visual processings.