Fergus I. M. Craik

Levels of processing: A framework for memory research

This paper briefly reviews the evidence for multistore theories of memory and points out some difficulties with the approach. An alternative framework for human memory research is then outlined in terms of depth or levels of processing. Some current data and arguments are reexamined in the light of this alternative framework and implications for further research considered.

Bilingualism, Aging, and Cognitive Control: Evidence From the Simon Task

Previous work has shown that bilingualism is associated with more effective controlled processing in children; the assumption is that the constant management of 2 competing languages enhances executive functions (E. Bialystok, 2001). The present research attempted to determine whether this bilingual advantage persists for adults and whether bilingualism attenuates the negative effects of aging on cognitive control in older adults. Three studies are reported that compared the performance of monolingual and bilingual middle-aged and older adults on the Simon task. Bilingualism was associated with smaller Simon effect costs for both age groups; bilingual participants also responded more rapidly to conditions that placed greater demands on working memory. In all cases the bilingual advantage was greater for older participants. It appears, therefore, that controlled processing is carried out more effectively by bilinguals and that bilingualism helps to offset age-related losses in certain executive processes.

The effects of divided attention on encoding and retrieval processes in human memory.

The authors examined the effects of divided attention (DA) at encoding and retrieval in free recall, cued recall, and recognition memory in 4 experiments. Lists of words or word pairs were presented auditorily and recalled orally; the secondary task was a visual continuous reaction-time (RT) task with manual responses. At encoding, DA was associated with large reductions in memory performance, but small increases in RT; trade-offs between memory and RT were under conscious control. In contrast, DA at retrieval resulted in small or no reductions in memory, but in comparatively larger increases in RT, especially in free recall. Memory performance was sensitive to changes in task emphasis at encoding but not at retrieval. The results are discussed in terms of controlled and automatic processes and speculatively linked to underlying neuropsychological mechanisms.

Age-Related Differences in Neural Activity during Memory Encoding and Retrieval: A Positron Emission Tomography Study

Positron emission tomography (PET) was used to compare regional cerebral blood flow (rCBF) in young (mean 26 years) and old (mean 70 years) subjects while they were encoding, recognizing, and recalling word pairs. A multivariate partial-least-squares (PLS) analysis of the data was used to identify age-related neural changes associated with (1) encoding versus retrieval and (2) recognition versus recall. Young subjects showed higher activation than old subjects (1) in left prefrontal and occipito-temporal regions during encoding and (2) in right prefrontal and parietal regions during retrieval. Old subjects showed relatively higher activation than young subjects in several regions, including insular regions during encoding, cuneus/precuneus regions during recognition, and left prefrontal regions during recall. Frontal activity in young subjects was left-lateralized during encoding and right-lateralized during recall [hemispheric encoding/retrieval asymmetry (HERA)], whereas old adults showed little frontal activity during encoding and a more bilateral pattern of frontal activation during retrieval. In young subjects, activation in recall was higher than that in recognition in cerebellar and cingulate regions, whereas recognition showed higher activity in right temporal and parietal regions. In old subjects, the differences in blood flow between recall and recognition were smaller in these regions, yet more pronounced in other regions. Taken together, the results indicate that advanced age is associated with neural changes in the brain systems underlying encoding, recognition, and recall. These changes take two forms: (1) age-related decreases in local regional activity, which may signal less efficient processing by the old, and (2) age-related increases in activity, which may signal functional compensation.

Aging and Cognitive Processes

1 Neuroanatomical and Clinical Neuropsychological Changes in Aging and Senile Dementia.- Aging: Normal versus Pathological.- Neuroanatomical Changes.- Electron Microscope Observations.- Light Microscope Changes.- Gross Changes.- Clinical Neuropsychological Changes.- Conclusions.- References.- 2 Cellular Mechanisms of Alzheimers Disease.- References.- 3 Advances in the Psychophysiology of Aging.- Novel Descriptive Techniques: Windows into the Brain.- Event-Related Potentials.- Computerized Axial Tomography.- Intervention: Plasticity in the Aging.- Conclusions.- References.- 4 A Neuropsychological Approach to Perception and Memory in Normal and Pathological Aging.- Visual Perception: The Effects of Backward Masking on the Identification of Letters and Words.- Primary and Secondary Memory: Free Recall, Cued Recall, and Recognition of Words and Faces.- Procedural or Skill Memory.- Remote Memory.- Memory in Everyday Life.- Summary.- References.- 5 How Do Old People Know What to Do Next?.- Passive and Active Control of Momentary Changes in Selective Attention.- Recency Effects Determined by Stimulus Characteristics or by Previously Learned Associations.- Control of Efficient Interrogation of the Environment.- Search of Probable before Improbable Locations in Space.- Guiding Search on the Basis of Cues from Neighboring Background Items.- Detection of Possibilities for Developing and Using Optimal Scanning Strategies.- Detection of Constant Probability Bias and of Sudden Changes in the Relative Probabilities of Events.- Remembering What to Do Next.- Failures to Index Immediate Memory to Maintain Control in a Serial Task.- Conclusions.- References.- 6 The Development of Visual Information Processes in Adulthood and Old Age.- A Visual Information Processing Model.- Developmental Questions.- Peripheral Perceptual Processes.- Central Perceptual Processes.- Selective Attention and Pattern Recognition.- Developmental Implications.- References.- 7 The Appearance and Disappearance of Age Differences in Adult Memory.- Summary of Present Research.- Integration with Previous Research.- Conclusions.- References.- 8 General Encoding of Episodic Events by Elderly Adults.- Experiment 1.- Experiment 2.- Experiment 3.- Conclusions.- References.- 9 Learning and Memory Deficits in Institutionalized and Noninstitutionalized Old People: An Analysis of Interference Effects.- Interference.- Control of Learning and Memory Deficits.- Brain Mechanisms.- Empirical Studies.- Subjects.- Interference and Learning.- Cuing Effects.- Memory.- Concluding Comments.- References.- 10 Encoding Deficits in Aging.- References.- 11 Aging and Cognitive Deficits: The Role of Attentional Resources.- Theoretical Background.- Empirical Studies.- Aging and Divided Attention.- Depth of Processing and Aging.- Age Differences in Semantic Memory.- Summary of Empirical Results.- Conclusions: Possible Reasons for Age Decrements in Memory.- References.- 12 Classification Style Differences in the Elderly.- Method.- Subjects.- Materials.- Procedure.- Measures.- Results.- Discussion.- References.- 13 Changes with Age in Problem Solving.- The Longitudinal Study of Concept Problem Solving.- Results.- Summary of Results.- Current Status and Future Directions.- References.- 14 The Theory of Fluid and Crystallized Intelligence in Relation to Concepts of Cognitive Psychology and Aging in Adulthood.- Major Concepts.- Some General Features of Procedures.- A Few Comments in Defense of Procedures.- Subjects and Variables.- Subjects.- Variables.- Analyses and Results.- Sensory Detection in Relation to Decline of Intellectual Capacities.- Short-Term Memory, Concentration, Attendveness, and Speediness Related to Gf Decline.- Speediness, Carefulness, and Persistence in Relation to Gf Decline.- Spontaneous Alertness, Expectations, and Incidental Memory.- Multiple-Process Involvements in Gf Decline.- The Rise of Crystallized Intelligence.- Summing Up.- Brain Function in Relation to Gf and Gc.- Gf Relations to Neurological Gating Functions.- Possible Neurological Underpinnings of Gc in Relation to Total Function.- Lateralization Theory in Relation to Gf/Gc Theory.- Summary.- References.- 15 Reallocation of Mental Resources over the Productive Lifespan: Assumptions and Task Analyses.- Overview.- Assumptions in Empirical Cognitive Gerontology: Subject-Selection Practices.- The Comparability Problem.- The Volunteer Problem.- A Study of Cognition, Age, and Voluntarism.- Subject Selection and Classification.- Selection and Theoretical Classification of Tasks.- General Results.- Overall Conclusions and Theoretical Analysis.- References.- 16 Attention Switching in Higher Mental Process.- References.- 17 Studying Cognitive Performance in the Elderly: A Biopsychosocial Approach.- The Biological Issues.- The Nature of Normal Biological Aging.- Non-Specific Presentation of Illness in the Elderly.- Drugs and the Elderly.- The Epidemiology of Senile Dementia.- Social Psychological Issues.- Selection Bias.- The Epiphenomena of Aging.- Labeling and Learned Helplessness.- The Problem of Ecological Validity.- Conclusions.- References.- 18 Memory Functioning in Late Adulthood.- Five Problems of Potential Significance.- Fear of Memory Impairment.- The Meaning and/or Accuracy of Self-Assessment of Memory Problems.- The Progress of Memory Disability.- The Subjective Experience of Memory Impairment and the Strategies Employed.- Potential Effects of Self-Perceived and Attributed Memory Problems on Self-Concept and on Interpretations of Behavior.- Content of Memories in Old Age: Case Studies.- Case 1.- Case 2.- Case 3.- Case 4.- Case 5.- References.- 19 Plasticity and Enhancement of Intellectual Functioning in Old Age: Penn States Adult Development and Enrichment Project (ADEPT).- Objectives of ADEPT.- On Variability and Plasticity in Intellectual Aging.- Variability.- Plasticity.- Context and Hypotheses of ADEPT Research.- Intellectual Aging: Role of Performance Factors and Ecological Deficits.- Theory of Fluid-Crystallized Intelligence as Framework.- General Design Characteristics.- Subjects.- Measurement Battery.- Rationale and Substance of Training.- Assessment of Training.- Results of Intervention Studies.- Retesting or No-Feedback Practice.- Training of Figurai Relations Ability.- Training of Induction.- Training of Attention/Memory.- Conclusions.- Retest Effects.- Ability-Specific Training and Transfer.- Implications: Toward an Integrative View.- Summary.- References.

Cognitive control and lexical access in younger and older bilinguals.

Ninety-six participants, who were younger (20 years) or older (68 years) adults and either monolingual or bilingual, completed tasks assessing working memory, lexical retrieval, and executive control. Younger participants performed most of the tasks better than older participants, confirming the effect of aging on these processes. The effect of language group was different for each type of task: Monolinguals and bilinguals performed similarly on working memory tasks, monolinguals performed better on lexical retrieval tasks, and bilinguals performed better on executive control tasks, with some evidence for larger language group differences in older participants on the executive control tasks. These results replicate findings from individual studies obtained using only 1 type of task and different participants. The confirmation of this pattern in the same participants is discussed in terms of a suggested explanation of how the need to manage 2 language systems leads to these different outcomes for cognitive and linguistic functions.

In Search of the Self: A Positron Emission Tomography Study

Previous work using positron emission tomography (PET) has shown that memory encoding processes are associated with preferential activation of left frontal regions of the brain, whereas retrieval processes are associated predominantly with right frontal activations. One possible reason for the asymmetry is that episodic retrieval necessarily involves reference to the self, and the self-concept may be represented (at least partially) in right frontal regions. Accordingly, the present study investigated the possibility that encoding of self-related material might also activate right frontal areas. Eight right-handed volunteers judged trait adjectives under four separate PET scan conditions: (a) relevance to self, (b) relevance to a well-known public figure, (c) social desirability, and (d) number of syllables. The results showed that self-related encoding yielded left frontal activations similar to those associated with other types of semantic encoding, but also specific activations in the right frontal lobe. It is concluded that the concept of self involves both general schematic structures and further specific components involved in episodic memory retrieval.

The role of rehearsal in short-term memory

Several widely accepted models of memory postulate that the adequacy of an items registration in long-term storage is a positive function of its length of stay in the short-term store. However, when short-term storage times were measured, these times did not predict long-term recall or recognition. Two further experiments showed that neither the length of an items stay in short-term storage nor the number of overt rehearsals it received was related to subsequent recall. It is concluded that the “maintenance” and “elaborative” aspects of rehearsal can be clearly separated, and that the duration of rehearsal is related to long-term memory and learning only in the latter case. Maintenance rehearsal does not lead to an improvement in memory performance.

Bilingualism as a protection against the onset of symptoms of dementia

This study examined the effect of lifelong bilingualism on maintaining cognitive functioning and delaying the onset of symptoms of dementia in old age. The sample was selected from the records of 228 patients referred to a Memory Clinic with cognitive complaints. The final sample consisted of 184 patients diagnosed with dementia, 51% of whom were bilingual. The bilinguals showed symptoms of dementia 4 years later than monolinguals, all other measures being equivalent. Additionally, the rate of decline in Mini-Mental State Examination (MMSE) scores over the 4 years subsequent to the diagnosis was the same for a subset of patients in the two groups, suggesting a shift in onset age with no change in rate of progression.

Levels of processing: past, present. and future?

In this article I first briefly survey some enduring legacies of the Craik and Lockhart (1972) article on levels of processing (LOP) and address some common criticisms. In the next section I discuss whether memory can be regarded as “pure processing”, the role of short-term memory in an LOP framework, measurement of “depth” in LOP, encoding-retrieval interactions, the concept of consolidation, and the reality of “levels” of processing. In the final section I offer some speculations on future directions, discussing the notion of levels of representation and a possible continuing role for LOP in memory research.