Inhibition in the processing of garden-path sentences.

The Hartman and Hasher (1991) garden-path sentence completion task has been used in several studies to assess the efficiency of the deletion function of inhibition (e.g., L. Hasher, R. Zacks, & C. P. May, 1999 ), with results suggesting that younger adults are efficient at suppressing once relevant but no longer appropriate information, whereas older adults generally are not (e.g., M. Hartman & L. Hasher, 1991: L. Hasher. M. B. Quig, & C. P. May, 1997; C. P. May & L. Hasher, 1998). An alternative interpretation of patterns of access to relevant and no-longer-relevant sentence endings focuses on the difficulty of selecting final words for sentence frames and on integration effects in implicit memory (M. Hartman, 1995). This alternative is considered and found wanting on the basis of both new and old empirical data. On the basis of present data and related findings, it is concluded that the task does measure inhibitory efficiency.

Source memory and eyewitness suggestibility in older adults.

The authors investigated the influence of test format on the source-memory performance of older adults (N = 128). Each participant viewed a picture and wrote a description of the scene. Then half of the participants (control group) read a text that accurately described the scene; the other half (misled group) read a text that contained misinformation. After writing another scene description, the participants were given a surprise memory test. Half were given a yes/no recognition test, and half were given a source-monitoring test. The misled yes/no participants mistakenly indicated more often than the control yes/no participants that misleading-text items were in the picture (suggestibility effect). There was no suggestibility effect for source-monitoring participants. The data are discussed in terms of the source monitoring framework.

Generation effects and source memory in healthy older adults and in adults with dementia of the Alzheimer type.

Recognition and source memory were explored in healthy older adults, adults diagnosed with very mild dementia of the Alzheimer type (DAT), and adults diagnosed with mild DAT. Two sentence-completion tasks were used. In Task 1, half of the sentences were completed (clozed) by the participant, and half by the experimenter. In Task 2, half were participant clozed, and half were participant read (already clozed). Recognition of the cloze words and accuracy of categorizing them as participant generated or experimenter generated (Task 1) and participant generated or participant read (Task 2) were measured (source discrimination). Contrary to previous reports, the DAT groups showed the generation effect, that is, better recognition for participant-generated words than experimenter-generated words (Task 1) or read words (Task 2). Source discrimination was disproportionately impaired in the DAT groups.

Implications of aging, lexicality, and item length for the mechanisms underlying memory span.

Hulme, Maughan, and Brown (1991) provided evidence that the contribution of long-term memory to memory span performance was additive to the contribution of rehearsal rate (e.g., Baddeley, 1986). The present study further explored the relationship between these two contributions in younger and older adults. Speech rates and spans for short, medium, and long words and nonwords were obtained from subjects. Older adults had slower speech rates and smaller spans than did younger adults. Both groups' data were fit well by linear functions relating speech rates to spans. However, the slope of the function that relates speech rate to memory span was greater for words than for nonwords. This finding supports the idea that long-term memory, as well as rehearsal rate, contributes to span performance, and that this contribution is not simply additive.

Aging, source, and decision criteria: when false fame errors do and do not occur.

Two experiments investigated the influence of decision criteria on source memory performance of older adults and younger adults. Experiment 1 used the false fame paradigm, which encourages people to use relatively loose decision criteria when making what are, in essence, source judgments. Consistent with previous research, older adults made more false fame errors than younger adults. Experiment 2 was identical to Experiment 1 except that the fame judgments were made with the traditional source task format that encourages relatively stringent decision criteria when making source judgments: Possible sources were listed, and participants categorized names in terms of their source. In contrast to Experiment 1, older adults reduced their false fame errors to the level of younger adults. Encouraging older adults to use relatively stringent decision criteria when making source discriminations can reduce age differences in source misattributions.

Cognitive test profile analysis for the identification of dementia of the Alzheimer type.

Two measures of profile similarity have been derived that offer complementary information about the classification of patients with diagnoses of probable dementia of the Alzheimer type (DAT). These measures were obtained for 31 probable DAT patients and 31 age- and education-matched controls using a set of six newly constructed cognitive scales designed to provide reliable measurement in both patient and control groups. A measure assessing similarity to the average performance of the controls provided perfect separation of the patient and control groups. A measure assessing similarity to the average performance of the probable DAT patients identified up to four atypical cases of probable DAT. One of these four cases has come to autopsy and was found to have Pick disease. The cognitive profiles of this Pick patient and an autopsy-confirmed DAT patient are compared to illustrate the potential advantages of using DAT patients as the reference group for profile analysis.