Judgments of frequency and recency: how they relate to reports of subjective awareness.

In 2 experiments, the author explored the relations of remember versus familiar ratings to judgments of frequency (JOFs) and to judgments of recency (JORs). In both cases, remembered items were associated with more accurate memory judgments. In general, familiar items were judged to have occurred less frequently and less recently than remembered items. However, JOFs and JORs associated with familiar items were more accurate than chance. Implications for theories of remember versus familiar ratings, JOFs, and JORs are considered. Some basic findings that constrain these theories are that (a) remember versus familiar ratings were less sensitive than JOF to presentation frequency and less sensitive than JOR to recency and (b) although remember versus familiar ratings are strongly related to both JOF and JOR, as measured by gamma, the relations are far from perfect.

Similarity, global matching, and judgments of frequency.

In the test-pair similarity effect, forced-choice recognition is more accurate for similar test pairs, such as leopard-cheetah, than it is for unrelated test pairs, such as leopard-turnip. According to global matching models, this occurs because the retrieved familiarities of similar items are correlated. In the Minerva 2 model, global matching underlies frequency judgments as well as recognition memory. One implication of this model is that judged frequencies of similar items should be correlated. Another implication is that judgments of summed frequency for pairs of words (how many presentations were there of word1 and word2 combined?) should have higher variance when word1 and word2 are similar than when they are unrelated. These predictions were tested and confirmed in two experiments. A review of these and other results suggests that theories of recognition memory should also be applicable to frequency-judgment tasks.

Retrieval dynamics in recognition and list discrimination: further evidence of separate processes of familiarity and recall.

Two experiments tested the hypothesis that the time course of retrieval from memory is different for familiarity and recall. The response-signal method was used to compare memory retrieval dynamics in yes-no recognition memory, as a measure of familiarity, with those of list discrimination, as a measure of contextual recall. Responses were always made with regard to membership in two previous study lists. In Experiment 1 an exclusion task requiring positive responses to words from one list and negative responses to new words and words from the nontarget list was used. In Experiment 2, recognition and list discrimination were separate tasks. Retrieval curves from both experiments were consistent, showing that the minimal retrieval time for recognition was about 100 msec faster than that for list discrimination. Repetition affected asymptotic performance but had no reliable effects on retrieval dynamics in either the recognition or the list-discrimination task.

Violations of the independence assumption in process dissociation.

L. L. Jacoby, J. P. Toth, and A. P. Yonelinas (1993) advocated a process-dissociation procedure for estimating the contributions to task performance of consciously controlled (R) versus automatic (A) memory processes. The procedure relies on the strong assumption that memory-guided performance attributable to R is stochastically independent of that attributable to A. Violations of this independence assumption can produce artifactual dissociations between estimates of R and A. Such artifactual dissociations were obtained in a series of word-stem completion experiments: R increased with presentation duration, whereas A, paradoxically, decreased. Direct evidence for nonindependence was obtained from correlations between R and A in each of the experiments. These results suggest that the independence assumption was violated, and other applications of process dissociation should not be taken at face value without a thorough evaluation of independence.

When encoding fails: instructions, feedback, and registration without learning.

Four experiments replicated and extended the registration-without-learning effect, in which there is little improvement in the ability to discriminate an old target (X) from a highly similar test item (Y) after the first few presentations of X, even though judgments of frequency continue to rise in an open-ended fashion. Forced-choice testing revealed the anomalous form of the learning curve for X-Y discrimination (faster and then slower than the exponential). Effects of several different learning instructions were compared, but these appeared to affect only the level of initial learning, and to do little to promote X-Y discrimination learning on later presentations. The opportunity for self-testing with feedback during study provided no benefits when responding was covert, but did when overt anticipation was required. The findings are discussed in relation to the roles of bottom-up and top-down processing in memory encoding, and to the importance of error-correcting feedback in further structural learning of materials, once the materials have become familiar.

On variability, Simpson's paradox, and the relation between recognition and recall: reply to Tulving and Flexser.

Tulving and Flexser's (1992) defense of the Tulving-Wiseman law rests on the partitioning of data points into 2 sets, which they call constrained and unconstrained. This dichotomy depends crucially on the implicit assumption that within-condition variance is 0. Simulations are done to show the effects of variability on the maximum contingency that can be displayed by an average 2 x 2 table. The results help explain the form of the regularity known as the Tulving-Wiseman law, as well as the conditions under which exceptions are found. This analysis reinforces the conclusion that the law is an artifact and serves as a reminder of the dangers posed by variability and Simpson's paradox when contingency analyses are done.

Effects of similarity and repetition on memory: registration without learning?

We investigated judgments of the frequency of test items (Y) that were highly similar to studied items (X) to test a prediction made by several memory models: that the judged frequency of Y should be proportional to the judged frequency of X. Whether stimuli were pictures or words, judged frequency of Y was bimodally distributed with 1 mode at zero, suggesting that frequency judgments involve a 2-stage process in which a zero judgment is made if there is a mismatch between retrieved information and the test item. Nonzero judgements, taken by themselves, were consistent with the prediction of proportionality. In 2 experiments, the percentage of zero judgments made to Y increased with repetition of X, but in 2 others the percentage did not change beyond frequency = 1. The percentage of "new" judgments in recognition memory followed this same pattern. Because the judged frequency of X increased even as X-Y discrimination showed no improvement, we characterize the result as "registration without learning."

Voluntary attention and the spacing effect.

Three experiments were done to test the hypothesis that the spacing effect results from a voluntary decision by the subject to pay little attention to the second presentation (P2) of an item when it occurs shortly after the first (P(1))- In all three experiments, the spacing of repetitions was varied. In Experiment I, allocation of attention was manipulated by pairing P2 of some pictures with a signal that indicated high payoff for later retention. In Experiment II, attention was controlled more directly by requiring the subject, in one condition, to recite words aloud. In both experiments, the dependent variable was judged frequency. In neither experiment did the effect of the attention manipulation interact with that of the spacing of repetitions. In Experiment III, the number of eye fixations given a picture was taken to be a measure of attention. The number of fixations dropped from P1 to P2 to P3, but was unaffected by the spacing of repetitions. The experiments provide no support for a voluntary attention explanation of the spacing effect.

What causes the spacing effect? Some effects of repetition, duration, and spacing on memory for pictures.

Three experiments examined effects of the spacing of repetitions on memory for pictures. In Experiment I, the duration of the first presentation (P(1)) was manipulated, as was P(1)-P(2) spacing. The effect of spacing on judged frequency was independent of P(1) duration. In Experiment II, pictures were given M massed presentations just prior to the P(M)-P(M+1) spacing interval. The form of the spacing curve was independent of M. Neither experiment confirmed the prediction of "overhabituation," derived from the habituation-recovery explanation of the spacing effect. In Experiment III, subjects made both duration and frequency judgments. The duration judgment results were not consistent with the notion that subjects remember multiple massed presentations as single occurrences of especially long duration. Some evidence from Experiments I and III suggests that an interrupted stimulus is recognized better than one that is not interrupted-a finding that, if replicable, would support the habituation-recovery account of the spacing effect.

Spacing effects in picture memory.

Three experiments were conducted to capitalize on the conclusion of Shaffer and Shiffrin (1972) that complex visual scenes are not rehearsed in testing the hypothesis that the effect of spacing on memory is due to rehearsal. In Experiment I, a list of vacation slides was presented in which both the number of repetitions and the spacing of repetitions were varied. Subsequent frequency judgments showed an effect of spacing much like that found using verbal materials. In Experiments II and III, effects of filled and unfilled spacing intervals were compared, and it was concluded that the spacing effect is primarily a function of the duration of the spacing interval. No evidence was found to support the notion that pictures are rehearsed. Rehearsal apparently cannot play the key role in an adequate, completely general explanation of the spacing effect.