Eye-movement control during learning and scanning of English pseudoword stimuli: Exposure frequency effects and spacing effects in a visual search task.

Wang et al. (Attention, Perception, and Psychophysics, in press, 2021) reported a Landolt-C learning and scanning experiment. In a learning session, they simulated exposure frequency effects successfully by training participants to learn target Landolt-C clusters with different exposures. The rate of learning high-frequency (HF) targets were greater than that of learning low-frequency (LF) targets. In a subsequent scanning session, participants were required to scan text-like Landolt-C strings to detect whether any pre-learnt target was embedded in the strings. The Landolt-C strings were displayed under different spacing formats (i.e., spaced format, unspaced format, and unspaced shaded format). However, the simulated exposure frequency effect did not occur in the scanning session. Wang et al. argued one straightforward reason for this might be because participants failed to maintain the memory of pre-learnt target to the scanning session. In the current study, we employed the same learning and scanning paradigm to investigate whether exposure frequency would occur in a target search task by using easier learning materials - pseudoword stimuli. The learning of pseudoword stimuli was much more successful than Landolt-C stimuli. Interestingly, however, we found a very different rate of learning effect such that the rate of learning LF targets was greater than HF targets. To our surprise, we did not find any influence of exposure frequency on eye movements during scanning even when participants were able to identify pre-learnt pseudowords in strings. Learning rate effect, exposure frequency effects, and saccadic targeting during the scanning of strings under different spacing formats are discussed in this paper.