Explorations of familiarity produced by words with specific combinations of letters

Phonological false recognition produced by bottom-up automatic activation in young and older people

Two experiments explored a new procedure to implicitly induce phonological false memories in young and older people. On the study tasks, half of the words were formed from half of the letters in the alphabet, whereas the remaining words were formed from all the letters in the alphabet. On the recognition tests, there were three types of non-studied new words: critical lures formed from the same half of the letters as the studied words; distractors formed from the other half of the letters not used, and distractors formed from all the letters in the alphabet. In both experiments, the results showed that, in both young and older people, critical lures produced more false recognitions than distractors composed of all the letters in the alphabet, which, in turn, produced more false alarms than distractors composed of the letters not used during the study. These results support the predictions of the activation/monitoring models, which assume that false memories are partly due to activation spreading from items (semantically or phonologically) related to the critical words.

Associative and Implicit Memory Performance as a Function of Cognitive Reserve in Elderly Adults with and without Mild Cognitive Impairment

This study aims to analyze implicit and explicit memory performance as a function of cognitive reserve (CR) in a healthy control group (N = 39) and a mild cognitive impairment (MCI) group (N = 37). Both groups were subdivided into high and low cognitive reserve, and were asked to complete an explicit and implicit associative recognition tasks. The results showed that the control group was able to learn both tasks (η2 = .19, p < .0001), and the high CR group fared better (η2 = .06, p < .05). The MCI sample, conversely, was unable to learn the implicit relationship, and showed very little learning on the explicit association task. Participants diagnosed with MCI showed little plasticity in learning associations regardless of CR (η2 = .12, p < .01).

Manipulating letter fluency for words alters electrophysiological correlates of recognition memory

The mechanisms that give rise to familiarity memory have received intense research interest. One current topic of debate concerns the extent to which familiarity is driven by the same fluency sources that give rise to certain implicit memory phenomena. Familiarity may be tied to conceptual fluency, given that familiarity and conceptual implicit memory can exhibit similar neurocognitive properties. However, familiarity can also be driven by perceptual factors, and its neural basis under these circumstances has received less attention. Here we recorded brain potentials during recognition testing using a procedure that has previously been shown to encourage a reliance on letter information when assessing familiarity for words. Studied and unstudied words were derived either from two separate letter pools or a single letter pool ("letter-segregated" and "normal" conditions, respectively) in a within-subjects contrast. As predicted, recognition accuracy was higher in the letter-segregated relative to the normal condition. Electrophysiological analyses revealed parietal old-new effects from 500-700 ms in both conditions. In addition, a topographically dissociable occipital old-new effect from 300-700 ms was present in the letter-segregated condition only. In a second experiment, we found that similar occipital brain potentials were associated with confident false recognition of words that shared letters with studied words but were not themselves studied. These findings indicate that familiarity is a multiply determined phenomenon, and that the stimulus dimensions on which familiarity is based can moderate its neural correlates. Conceptual and perceptual contributions to familiarity vary across testing circumstances, and both must be accounted for in theories of recognition memory and its neural basis.

The role of perceptual information in familiarity-based scene recognition

A method to analyze the role of familiarity in recognizing pictures of everyday scenes is introduced. The idea is to manipulate two within-subjects conditions: an experimental condition where the scenes repeat perceptual information (e.g. buildings and/or vehicles) and a control condition. The results show the two conditions did not differ in terms of hit rates, but in the experimental condition there were significantly fewer false alarms, yielding better results, which supports the findings of past research studies that have used verbal materials. This perceptual facilitation was maintained throughout a week-long retention interval. Finally, a detailed analysis of this facilitation shows it was due to a significant reduction in false alarms on know judgments, emphasizing familiarity's role in explaining this effect.

Measuring recollection and familiarity: Improving the remember/know procedure

The remember/know (RK) procedure is the most widely used method to investigate recollection and familiarity. It uses trial-by-trial reports to determine how much recollection and familiarity contribute to different kinds of recognition. Few other methods provide information about individual memory judgements and no alternative allows such direct indications of recollection and familiarity influences. Here we review how the RK procedure has been and should be used to help resolve theoretical disagreements about the processing and neural bases of components of recognition memory. Emphasis is placed on procedural weaknesses and a possible confound of recollection and familiarity with recognition memory strength. Recommendations are made about how to minimise these problems including using modified versions of the procedure. The proposals here are important for improving behavioural and lesion research, and vital for brain imaging work.

Familiarity changes as a function of perceptual shifts

This experiment compares the yes-no and forced recognition tests as methods of measuring familiarity. Participants faced a phase of 3 study-test recognition trials in which they studied words using all the letters of the alphabet (overlapping condition, O), and an additional phase in which targets and lures did not share any letters (non-overlapping condition, NO). Finally, subjects performed a forced-choice task in which they had to choose one of two new words, each from one of the subsets (Parkin et al., 2001). Results in the NO condition were better than in the O condition in the yes-no recognition test, while the forced-choice rate was significantly higher than .50, showing their sensitivity to familiarity. When the letter set of the words for study in the third list of the NO condition was switched, the difference between NO and O conditions disappeared in yes-no test, while the force-choice rate was not higher than .50. We conclude that both the yes-no test and the forced-choice test are valid and equivalent measures of familiarity under the right conditions.