Encoding variability accounts for false recognition of noncorresponding lures on the forced-choice Mnemonic Similarity Task

Abstract

On forced-choice tests of recognition memory, performance is best when targets are paired with novel foils (A-X), followed by corresponding lures (A-A'), and then noncorresponding lures (A-B'). The current study tested the prediction that encoding variability accounts for reduced performance on A-B' trials. Young adults (n = 43) completed the forced-choice Mnemonic Similarity Task while eye movements were recorded. Errors on the A-B' test format were attributable to encoding variability; incorrect A-B' trials were associated with more fixations to the B stimulus than the A stimulus at encoding. However, encoding variability did not account for accuracy on the A-A' test format.

Figure 1.

Memory performance in each test format of the forced-choice MST. Error bars reflect standard errors. * indicates p < 0.05.

Figure 2.

Effect of mnemonic similarity on memory performance. Error bars reflect standard errors. * indicates p < 0.05.

Figure 3.

Mean fixation counts at encoding for stimuli subsequently included in the A-B′ test format. Subsequently incorrect trials were associated with more fixations to the original version of the lure (B) than the target stimulus (A) at encoding. Fixation counts at encoding for the A and B stimuli did not differ for subsequently correct trials. Error bars reflect standard errors. * indicates p < 0.05.