Encoding specificity in the alcoholic Korsakoff patient

A previous attempt to improve amnesic Korsakoff patients' retention of individual words resulted in only moderate improvement and, then, only under restricted conditions. It appeared that this occurred because the patients “forget” the instructed analysis of the word as well as the word itself. Consequently, the two experiments reported here sought to provide feature (Experiment 1) or associated (Experiment 2) cues at both input and output. In this manner relatively good performance was obtained, but only when semantic cues were “strongly” associated to the target words. Implications for an encoding specificity interpretation are drawn from these results.     

Different patterns of mnemonic deficits in two organic amnestic syndromes

A recall and recognition memory study of Korsakoff and post-herpes encephalitis patients employing percentage correct recall and the statisticd′ derived from signal detection theory supports Lhermitte's contention that these two patient groups represent two distinct organic amnesia syndromes. Post-herpes encephalitis patients show little evidence of encoding and storage of information. In contrast recognition memory of Korsakoff and normal control subjects was essentially similar for truly novel information. Recognition memory for English words was markedly impaired for Korsakoff patients and worsened with increased semantic organization of the material. In light of our findings it would seem advisable to utilize homogeneous groups, with respect to brain pathology, when studying memory processes in organic patients.     

Alcoholic Korsakoff patients' retrieval from semantic memory

Alcoholic Korsakoff patients' rate of retrieval from semantic memory was investigated. It was found that their rate of retrieval from “lexical” semantic memory was nearly normal, but their rate of retrieval from “conceptual” semantic memory was impaired. In addition, an attempt to “prime” their lexical semantic memory by requesting the same category to be searched on adjacent trials met with failure. It was concluded that Korsakoff patients' lexical storage is probably organized normally, but their conceptual organization is not. Parallels with these patients' episodic memory impairments are discussed and possible interactions between episodic and semantic memory are proposed.     

Elaborative processing in the Korsakoff syndrome: context versus habit

Using a procedure of Hay and Jacoby [Hay, J. F., & Jacoby, L. L. (1999). Separating habit and recollection in young and older adults: Effects of elaborative processing and distinctiveness. Psychology and Aging, 14, 122–134], Korsakoff patients’ capacity to encode and retrieve elaborative, semantic information was investigated. Habits were created during initial training, whereupon cued-recall memory performance was examined, with habit opposing as well as facilitating recollection of earlier studied words. A first group of patients was instructed and tested in the same way as healthy controls and showed poor test performance. Nevertheless, when given more processing and response time, additional explanation, and explicit encouragement, a second group of patients performed similarly to healthy controls. The results suggest that, when given adequate support, Korsakoff patients are able to encode and make use of semantic, contextual, and sequential information. Word distinctiveness, however, only influenced performance of controls.     

Semantic knowledge as a determinant of developmental differences in recall

Two experiments examined the possible role of children's semantic knowledge and their ability to encode it in a cued-recall test. Performance of children aged 7, 10, and 13 was observed in encoding specificity tasks, which used homographs as the to-be-remembered words (TBRs).In Experiment I, children of all ages performed better when the output cue words prompted similar meanings to the input cues, than when output and input meanings were incompatible. In Experiment II, all children were required to recall identical items, but younger children, owing to lack of knowledge, were unable to encode pairs comprising input and TBR words incompatibly with output cues. In such circumstances, younger subjects outperformed older subjects. When input and output cues were incompatible for all ages, recall increased with age, possibly due to older childrens' using more effective retrieval strategies.The findings indicate that semantic encoding influenced recall performance at each age. This suggests that age differences in memory are due to differences in the amount of semantic knowledge a child possesses for encoding and cuing and not to capacity differences.     

Korsakoff amnesic syndrome: The result of simultaneous deficits in several independent processes?

Alcoholic Korsakoff patients were presented six verbal list learning tasks (two denotatively and three connotatively organized, and one high-imagery word list). Twelve recall trials and three recognition probes were obtained per list. Results indicate that for Korsakoff patients, (1) recall varied with list organization, (2) recognition memory although poor was further disrupted by proactive inhibition only on denotatively categorized lists, and (3) conceptual deficits disrupted ability to appreciate simple dichotomies in denotatively categorized lists. It is hypothesized that the joint presence of deficts in specific conceptual and semantic processes in necessary although perhaps not sufficient to produce a Korsakoff amnesia.     

Frontal lobe dysfunction and memory impairment in patients with chronic progressive multiple sclerosis

Deficits in semantic encoding have been described in patients with frontal lobe disease who also show memory impairments. As a group, patients with multiple sclerosis (MS) exhibit memory impairment, fail to make effective use of semantic encoding to aid memory, and perform poorly on verbal fluency and concept formation tests which are sensitive to frontal lobe damage. In the present study the semantic encoding capacity of MS patients was measured using a modification of Wicken's release from proactive interference (PI) paradigm. Individual patients varied considerably in the severity of their impairments on verbal fluency, verbal recognition memory and on Wisconsin Card Sorting Task, but even patients who evidenced both memory impairment and signs of frontal lobe dysfunction showed normal release from PI after a categorical shift. Memory disturbances in MS are unlikely to result from an incapacity for semantic encoding, which seems preserved in MS, but may arise instead from deficits in processing information rapidly.     

Representing logical and semantic structure of knowledge acquired from discourse

A network model of logical and semantic structures from which speakers or writers generate linguistic messages at the discourse level is presented. While linguistic structures were considered in developing the model, the semantic and logical networks are defined without reference to linguistic structures and thus may be used to represent knowledge structures acquired from both linguistic and nonlinguistic sources. A second problem addressed is that of determining what logical and semantic information is acquired when a text is understood. To assess acquired knowledge, a procedure is presented for coding a subject's verbal reconstruction of knowledge acquired from a presented text (or other input) against the logical and semantic structure from which the text (or other input) was derived. The procedures are illustrated using data obtained from children who were asked to “retell” simple narrative stories.     

Semantic field,naming, and auditory comprehension in aphasia

The status of semantic fields for 16 target nouns was compared in high and low comprehension aphasics, brain damaged, and normal controls, by measuring latency and miss rate for recognition of six classes of associates, which were presented orally on tape. The ability to name each target was also examined as a function of the integrity of the subject's semantic field for that word. Low comprehension aphasics showed both quantitative and qualitative changes in semantic fields, while milder aphasics showed only mild quantitative impairment, as compared to controls. Both latency and miss rate measures indicated that failure to name a word is associated with reduced semantic field for that word. This result is interpreted as supporting the view that nameing is, in part, determined by the convergence of associations.     

Affiliation of opposite-sexed strangers

This study examined the effects of a subject's sex and affiliative tendency and the other's physical attractiveness on the cross-sexual interaction of strangers. Although previous studies showed that one's interest in an opposite-sexed other is a function of the other's physical attractiveness, the actual behavior of individuals in the presence of attractive and unattractive others had not been systematically examined. Subjects were individually placed in a 5-min waiting situation with a physically attractive or unattractive target of the opposite sex who behaved in a standard way. Conversations were recorded and subsequently analyzed; subjects also provided their impressions of the targets following the waiting period. Physical attractiveness of the opposite-sexed other did not significantly influence the subject's verbal affiliative behavior, but the combined influence of a subject's sex and affiliative tendency was predictive of cross-sexual affiliation. Although physical attractiveness did not account for differences in affiliative behavior, subjects preferred attractive over unattractive targets as potential dates or marriage partners.     

Verbal retention deficits in aphasic and amnesic patients.

Five different groups of patients (aphasics, alcoholic Korsakoffs, nondominant hemisphere patients, alcoholics, and control patients) were asked to detect either repeated letters, repeated words, rhyming words, or words from the same category during the reading of a list. It was discovered that the number of intervening words had a greater effect on the aphasics for all conditions than it did for the other groups. However, when the rate of presentation was slowed, the aphasics showed considerable improvement while the other groups maintained their same level of performance. The Korsakoff patients were impaired only on the semantic task (same category inclusion) and did not improve at the slower presentation rate. An interpretation based on speed and level of information processing abilities is given.     

Strategic and automatic priming of semantic memory in alcoholic Korsakoff patients

To examine whether the organization of semantic memory is intact in alcoholic Korsakoff patients, three semantic memory tasks which do not require active search for stored information were administered to a group of Korsakoff patients and alcoholic controls. The first two tasks used a perceptual identification paradigm in which patients had to identify briefly presented targets preceded by associatively (experiment 1) or categorically (experiment 2) related primes. On both tasks, Korsakoff patients demonstrated intact priming effects. Because priming in these tasks was thought to reflect the operation of strategic processes, experiment 3 was designed to assess automatic spreading activation using a lexical decision task. Here as well, Korsakoff patients demonstrated intact priming. Taken together, these results support the view that the organization of semantic memory in Korsakoff patients has not been disrupted by their brain injury. The implications of these findings for understanding Korsakoff patients' impaired performance on semantic search tasks are discussed.     

Evaluative and taxonomic encoding in children's memory

The experiments were conducted to investigate the development of evaluative and taxonomic encoding in children's memory. The task used was a modification of the Wickens short-term memory task in which subjects' recall of words is tested following a distraction task. The first experiment found that 11-year-old children, but not 8-year-old children, encoded words using the evaluative dimension of the semantic differential. In the second experiment, both 7- and 11-year-olds demonstrated the ability to encode words according to taxonomic categories. These findings were related to other recent work on the development of encoding in memory.     

Left hemisphere superiority for pronounceable nonwords,but not for unpronounceable letter strings

Right-handed adults were asked to identify bilaterally presented linguistic stimuli under three experimental conditions. In Condition A, stimuli were three-letter pronounceable nonwords (such as TUP), and subjects were asked to report them by naming them. In Condition B, stimuli were three-letter pronounceable nonwords, and subjects were asked to report them as strings of letters. In Condition C, stimuli were more or less unpronounceable letter strings (such as UTP) created by rearranging the letters of pronounceable nonwords, and subjects reported them as strings of letters. Pronounceable nonwords were found to be better identified from the right visual hemifield irrespective of the way in which they were reported. Unpronounceable letter strings did not produce any visual hemifield difference. Nonwords are of interest because they can be seen as potential words that lack both specific semantic properties and entries in the subject's internal lexicon. The results of the experiment are consistent with the view that both the left and right cerebral hemispheres are able to identify letters but the left hemisphere is more sensitive to the pronounceability of the nonwords. This may happen either because the left hemisphere can make better use of resemblances to real words or because it has access to spelling to sound correspondence rules.     

Power and speed components of individual differences in letter matching

Several previous studies have reported a correlation (typically around −.30) between standardized verbal ability test scores and name identity minus physical identity reaction times (NI-PI) in a letter-matching task. This correlation has usually been thought to reflect the mutual dependence of both measures on long-term memory access time. The present research was designed to assess Carroll's (1981) suggestions that: (a) NI — PI may not be the optimal formula for predicting standardized test scores from letter matching data, and (b) NI — PI may actually be related to the speed rather than the power component of standardized tests. Fifty-one subjects previously tested with a standardized reading test participated in letter-matching and word-reading tasks. The latter tasks required subjects to read words and specially constructed pseudowords. Power and speed measures were derived from the word-reading tasks and the standardized test on theoretical grounds (and supported by a principal components analysis). The results supported both of Carroll's contentions. NI — PI reaction time was related more to speed than power and the NI — PI statistic (as usually used) was not the optimum formula for predicting standardized test scores.     

Lateralization of temporal lobe dysfunction and verbal encoding

The contribution of encoding deficits to verbal-learning difficulties known to be associated with temporal lobe dysfunction was investigated. Auditory and visual false-recognition tasks, which assess verbal encoding strategies, were given to patients with left-temporal-lobe (LTL) and right-temporal-lobe (RTL) surgical excisions and to a group of normal controls (NC). On both auditory and visual tasks, LTL patients made significantly more false-recognition errors than the other subjects on related, but not unrelated, words in the test list. The findings indicate that LTL patients are able to initially encode verbal material and that a breakdown in information processing occurs at a later stage. On the auditory tasks, the performance of RTL patients did not differ from that of NC subjects. However, on the visual tasks, RTL patients, as compared to both LTL and NC subjects, made fewer false-recognition errors. The performance of RTL patients, in contrast to LTL patients, could be interpreted as a reduced encoding of the visual attribute of verbal material. Another possible explanation considered was difficulty in familiarity discrimination.     

Verbal ability and mental processing speed

The notion that verbal ability is related to mental processing speed was examined using tasks that systematically varied in semantic content. Subjects' reaction times were measured in five tasks involving arrow matching, physical identity word matching, or taxonomic identity word matching. The findings indicated that matching tasks using different decision rules and different stimuli were all related to verbal ability. In fact, reaction time for subjects required to judge whether two arrows pointed in the same direction was the best predictor of verbal ability. One explanation of the results is that speed of information processing (a general factor) may be the important component of verbal ability which is measured by seemingly different matching tasks.     

Visual problem solving in the absence of lexical semantics: Evidence from dementia

A case of dissociation between visual and praxic skills and linguistic, referential, and semantic skills is described in a case of dementia. Testing revealed that her visual processing was intact and that she was capable of a wide range of visually based tasks. These included copying geometric figures and block designs; matching items on the basis of number, color, or relative size, matching upper and lower case letters, sequencing numerals, orienting pictures, coins, and letters appropriately, and solving problems based on the identification of geometric patterns or on the identification of logical sequences based on pattern alternation, number, and size increases. In contrast, she was completely incapable of matching pictures on the basis of their semantic or referential meaning; similarly she had lost all comprehension of language. It was argued that this case demonstrates the capacities of a visual system cut off from all symbolic and semantic processes. When examined with other case studies this case provides information about the nature of and interaction between modality-specific perceptual processing and semantic processing, and information about the various cognitive factors involved in visual gnosis. The CT scan indicated frontal atrophy and marked anterior temporal atrophy, a pattern that is consistent with Pick's disease. The case was discussed in terms of the correlation between the pattern of observed strengths and deficits and the neurological pattern of atrophy.     

Verbal ability and mental processing speed

The notion that verbal ability is related to mental processing speed was examined using tasks that systematically varied in semantic content. Subjects’ reaction times were measured in five tasks involving arrow matching, physical identity word matching, or taxonomic identity word matching. The findings indicated that matching tasks using different decision rules and different stimuli were all related to verbal ability. In fact, reaction time for subjects required to judge whether two arrows pointed in the same direction was the best predictor of verbal ability. One explanation of the results is that speed of information processing (a general factor) may be the important component of verbal ability which is measured by seemingly different matching tasks.