Number pairs were adapted from Moeller, Fischer, Nuerk, and Willmes (2009) and were balanced such that both relevant groups of stimuli (i.e. compatible versus incompatible trials) yielded statistically similar measures of multiple factors including overall numerical distance, unit distance, decade distance, problem size, correct hand response, and within-pair direction of numerical ordering.
In each solvent, there is a contraction along the alignment direction paired with an expansion in the perpendicular directions.
The direction normally shown in the target-present condition is plotted in green, the direction paired with the exact-target condition in blue, and the direction paired in the target-absent condition in red; the color code for directions is the same in all three graphs.
One motion direction temporally overlapped each target letter (paired-direction), and other directions temporally overlapped the distractors (non-paired directions).
The paired-direction was randomly chosen, from the testing set, for each subject.
Consistent with previous results [27], [29], improved performance was specific to the paired-direction.
In Seitz and Watanabe [4], the paired-direction can be viewed as a predictor of the RSVP target and the same signals that result in learning of paired-direction would be well-placed to form an association between the paired-direction and the task-targets.
However, it is possible that subjects learned to use the paired-direction as a cue that indicated to the subjects that the target was about to appear.
In this procedure (Figure 1), a sub-threshold motion-stimulus is temporally-paired with the targets of a letter identification task, and with many days of training on this task subjects develop improved sensitivity for the "paired-direction" when evaluated with tests of motion-direction discrimination [29].
