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PubMed1976

Differential association between chronic cannabis use and brain function deficits.

To summarize, 12 objective tests that generated 16 test variables were administered to 850 male regular cannabis users and 839 nonusers. The tests were designed to assess various modalities, including speed of psychomotor performance, distance estimation, time estimation, immediate memory, and visuomotor coordination. Most of the test variables differentiated significantly between consumers and controls. At the same time, a significant second-order interaction emerged in most cases. This interaction meant that, under certain conditions that relate to the two dimensions "literacy-illiteracy" and/or "urbanism-ruralism," the superiority of controls over cannabis users became impressive, whereas under other conditions it almost disappeared. To account for this complex pattern of results, a working hypothesis was presented to the effect that "other conditions being equal, the lower the nondrug level of proficiency on tests of cognitive and psychomotor performance the smaller the size of function deficit associated with drug usage." For an empirical examination of the hypothesis, six predictions were formulated. Three predictions defined specific relationships between level of performance, on one hand, and each of three organismic variables, on the other: literacy, urbanism, and age. The remaining predictions delineated relationships to be expected between size of function deficit and the three organismic variables. All our predictions were confirmed, showing less function impairment to be contingent with cannabis usage among the illiterates, rurals, and older subjects. Level of cortical arousal was suggested as the central process associated with the three organismic variables. Because the version of our working hypothesis was formulated with reference to chronic material, the possibility of a transposition of the paradign to research on the acute effects of the drug was discussed. The suggestion was made that our working hypothesis, in either version, is capable of establishing genuine integration between reports that present conflicting results on possible function deficits contingent with cannabis consumption.

Adolescent↗
PubMed1986

Deciding for others.

Decision making for incompetent elderly people is an increasingly serious issue for American society. The decision-making processes we choose will reflect choices among a number of ethical principles--those specifying the purpose of substituted judgment, those guiding the surrogate decision maker, and those used in choosing the surrogate--and depends as well on the way we construe the concept of decision-making competence.

Advance Directives↗
PubMed1991

Remembering less and inferring more: effects of time of judgment on inferences about unknown attributes.

Perceivers often infer the values of unknown attributes from evaluative expectancies. In 2 experiments, inferences about unknown attributes of a target made shortly after initial processing tended to be moderate, as perceivers presumably adjusted for the lack of directly relevant evidence. However, stronger inferences were drawn with the passage of time as memory of the absence of information faded. Expertise moderated this effect, as subjects highly knowledgeable of the target domain were much less likely than low or moderate knowledge subjects to draw extreme inferences over time. Memory-based inferences about unknown attributes were also found to be held with greater confidence than inferences made shortly after stimulus presentation.

Adult↗
PubMed2006

Electrophysiological correlates of retrieval processing: effects of consistent versus inconsistent retrieval demands.

Studies employing event-related potentials (ERPs) during tests of recognition memory have reported differences in neural activity elicited by new test items according to the specific demands of the retrieval task, such as retrieving studied words versus pictures. The present study investigated whether differential processing of new items is possible when retrieval demands vary unpredictably on a trial-by-trial basis. In separate study-test phases, subjects encoded lists of intermixed words and pictures, and undertook retrieval tests with words as test items. Each test item was preceded by a task cue that signaled whether subjects were to attempt to retrieve a word or a picture from the study list. In the "blocked"condition, the targeted study material remained constant throughout the test, whereas in the "mixed"condition, the targeted material varied unpredictably across trials. New-item ERPs were more positive-going when words rather than pictures were targeted in the "blocked" condition, replicating previous findings, but this effect was absent in the "mixed"condition. The findings are consistent with the hypothesis that differential processing of retrieval cues depends upon the adoption of different task sets ("retrieval orientations" that develop over multiple trials and cannot be adjusted merely in response to an instructional cue. Unlike the new-item ERPs, ERPs elicited by the task cues in the mixed condition differed according to targeted material, but only on trials when there was a switch between target material. The implications of these findings for understanding the different retrieval strategies engaged when retrieval demands are consistent versus inconsistent are discussed.

Adolescent↗
PubMed1983

Dreaming: The functional state-shift hypothesis. A neuropsychophysiological model.

The different brain functional states during sleep and wakefulness are associated with differences in processing strategies, memory stores, and EEG patterns. Shifts of functional state occur spontaneously or as orienting reactions to processed information, and cause the formal characteristics of dreams. Forgetting of dreams is a function of the magnitude of the difference between states during storage and recall. Based on EEG similarities between sleep stages and developmental stages, brain states during sleep in adults are proposed to correspond functionally with waking states during childhood. Repeated functional regressions occur during sleep, with access to earlier memory material and cognitive strategies unavailable during waking life, so that earlier experiences can be used for current problems. This dream work constitutes the biological significance of sleep.

Adolescent↗
PubMed2004

Coherence and specificity of information-processing biases in depression and social phobia.

Research has not resolved whether depression is associated with a distinct information-processing bias, whether the content of the information-processing bias in depression is specific to themes of loss and sadness, or whether biases are consistent across the tasks most commonly used to assess attention and memory processing. In the present study, participants diagnosed with major depression, social phobia, or no Axis I disorder, completed several information-processing tasks assessing attention and memory for sad, socially threatening, physically threatening, and positive stimuli. As predicted, depressed participants exhibited specific biases for stimuli connoting sadness; social phobic participants did not evidence such specificity for threat stimuli. It is important to note that the different measures of bias in memory and attention were not systematically intercorrelated. Implications for the study of cognitive bias in depression, and for cognitive theory more broadly, are discussed.

Adolescent↗
PubMed1992

Inference during reading.

Most current theories of text processing assume a constructionist view of inference processing. In this article, an alternative view is proposed, labeled the minimalist hypothesis. According to this hypothesis, the only inferences that are encoded automatically during reading are those that are based on easily available information, either from explicit statements in the text or from general knowledge, and those that are required to make statements in the text locally coherent. The minimalist hypothesis is shown to be supported by previous research and by the results of several new experiments. It is also argued that automatically encoded minimalist inferences provide the basic representation of textual information from which more goal-directed, purposeful inferences are constructed.

Attention↗
PubMed2004

Case representation by medical experts, intermediates and novices for laboratory data presented with or without a clinical context.

BACKGROUND: Based on cognitive psychological research, a number of theoretical frameworks have been put forward to describe the structure of experts' medical knowledge and to explain experts' case-processing. PURPOSE: To provide evidence for the theory of knowledge encapsulation, which states that medical knowledge constitutes of interlinked biomedical and clinical knowledge. METHODS: Fourth-year medical students, clerks and medical experts evaluated six case descriptions, consisting of laboratory data either with or without a clinical context. For each case description, the participants were required to study the case, to formulate a diagnosis, and to write down everything they could remember of the case. RESULTS: When the laboratory data were not embedded within a clinical context, medical experts' case-processing increased and their diagnostic accuracy became worse. Furthermore, laboratory data recall of medical experts was more elaborate in cases where the laboratory data were presented without a clinical context. Similar results were obtained for students and clerks. CONCLUSIONS: The findings are only partially consistent with a prediction made by the theory of knowledge encapsulation. Further research, using a different paradigm than the traditionally used method of free recall, is required to unearth whether medical experts use qualitatively different knowledge structures than novices while solving cases.

Clinical Competence↗
PubMed2006

Mentalizing and Marr: an information processing approach to the study of social cognition.

To interact successfully, individuals must not only recognize one another as intentional agents driven primarily by internal mental states, but also possess a system for making reliable and useful inferences about the nature of those beliefs, feelings, goals, and dispositions. The ability to make such mental state inferences (i.e., to mentalize or mindread) is the central accomplishment of human social cognition. The present article suggests that our understanding of how humans go about making mental state inferences will benefit from treating social cognition primarily as an information processing system that comprises a set of mechanisms for elaborating more basic social information into an understanding of another's mind. Following Marr's [Marr, D., 1982. Vision. W. H. Freeman, San Francisco, CA] framework for the study of such information processing systems, I suggest that questions about social cognition might profitably be asked at three levels--computation, algorithm, and implementation--and outline a number of ways in which a description of social cognition at the middle level (i.e., the step-by-step processes that give rise to mental state inferences) can be informed by analysis at the other two.

Cognition↗
PubMed1991

Image, issues, and ideology: the processing of information about political candidates.

Ss watched a videotaped nonpolitical speech by a male political candidate that conveyed either a favorable or an unfavorable image. Then they heard an excerpt of a radio program in which the candidate was described as holding either conservative positions or liberal positions on a series of specific issues. The impact of the candidate's speech on evaluations of him decreased over time. However, Ss used the speech as a basis for judgment only when the candidate's issue stands had unfavorable implications. When Ss learned the candidate's issue stands 24 hr after they heard the speech, they based their evaluations on their personal agreement with these stands. When Ss learned the candidate's issue positions immediately after the speech, however, they based their evaluations on the ideological implications of the issue stands instead.

Adult↗
PubMed1995

Double dissociation without modularity: evidence from connectionist neuropsychology.

Many theorists assume that the cognitive system is composed of a collection of encapsulated processing components or modules, each dedicated to performing a particular cognitive function. On this view, selective impairments of cognitive tasks following brain damage, as evidenced by double dissociations, are naturally interpreted in terms of the loss of particular processing components. By contrast, the current investigation examines in detail a double dissociation between concrete and abstract work reading after damage to a connectionist network that pronounces words via meaning and yet has no separable components (Plaut & Shallice, 1993). The functional specialization in the network that gives rise to the double dissociation is not transparently related to the network's structure, as modular theories assume. Furthermore, a consideration of the distribution of effects across quantitatively equivalent individual lesions in the network raises specific concerns about the interpretation of single-case studies. The findings underscore the necessity of relating neuropsychological data to cognitive theories in the context of specific computational assumptions about how the cognitive system operates normally and after damage.

Brain Damage, Chronic↗
PubMed1979

The interaction between age and list length in free recall.

Using the "delayed-recall" procedure developed by Shiffrin (1970), the effects of list length on encoding, storage, and retrieval processes in different aged subjects were assessed. The length of a list interpolated in the retention interval did not interact with age, while an interaction was found between age and the length of list being recalled. Age differences in the probability of recall decreased as the length of the list being recalled increased. This interaction was replicated in a second experiment with immediate recall. This interaction seems most compatible with the hypothesis that older persons use less spontaneous organization during list learning. List length primarily disrupts the ability of younger subjects to develop adequate organizational plans (2.e., longer lists are more difficult to organize), and because older subjects are organizing less, they are less affected by the increases in list length.

Adult↗
PubMed1995

Functional brain maps of retrieval mode and recovery of episodic information.

Positron emission tomography (PET) was used to identify brain regions associated with two component processes of episodic retrieval; those related to thinking back in subjective time (retrieval mode) and those related to actual recovery of stored information (ecphory). Healthy young subjects recognized words that had been encoded with respect to meaning or the speaker's voice. Regardless of how the information had been encoded, recognition was associated with increased activation in regions in right prefrontal cortex, left anterior cingulate, and cerebellum. These activations reflect retrieval mode. Recognition following meaning encoding was specifically associated with increased activation in left temporal cortex, and recognition following voice encoding involved regions in right orbital frontal and parahippocampal cortex. These activations reflect ecphory of differentially encoded information.

Adult↗
PubMed1991

Mentally retarded individuals--a population at risk?

When comparing the aging process of mentally retarded (MR) persons with the nondisabled population, researchers have established an earlier lower limit for the onset of old age for MR persons and a higher mortality rate. The reason for early senescence has not been successfully resolved, but the finding that cardiovascular disorders are the most prevalent form of disease among elderly MR persons suggests a relationship between lifestyles and higher mortality rate. Indeed, studies that evaluated the cardiovascular fitness (CVF) of MR individuals demonstrated substandard levels of fitness. The results of these studies, however, are not conclusive due to variation in test methodologies, motivational factors, and issues of test validity and reliability. Training studies which have purported to determine trainability of this population have also shown confusing results, perhaps attributed to the same protocol inconsistencies. Therefore, the purposes of this article are 1) to review previous methods of evaluating CVF of MR adults and determine whether testing methodologies invalidate the results of these studies, 2) to review training studies involving adult MR individuals and determine whether this population is capable of improving their CVF, and 3) to identify areas where further research is needed to fully describe the functional cardiovascular characteristics of MR adults.

Cardiovascular Diseases↗
PubMed1993

Item and relational processing in young and older adults.

The item and relational information framework of memory provided a methodology for an analytical approach to age differences in encoding and retrieval processes. Subjects were given related or unrelated words to sort or rate for pleasantness. Young adults performed better than older adults in free recall, but older adults were able to use both item and relational information as well as young adults. In a second experiment, subjects also sorted or rated a list composed of different numbers of category items. The pattern of free recall and cued recall scores indicated that item and relational information affected the memory performance of both age groups in a similar fashion. By examining memory in terms of item and relational information, it appears that older adults do not have difficulty combining two types of target information during encoding and that the information assists in recall of target items.

Adolescent↗
PubMed2002

Six views of embodied cognition.

The emerging viewpoint of embodied cognition holds that cognitive processes are deeply rooted in the body's interactions with the world. This position actually houses a number of distinct claims, some of which are more controversial than others. This paper distinguishes and evaluates the following six claims: (1) cognition is situated; (2) cognition is time-pressured; (3) we off-load cognitive work onto the environment; (4) the environment is part of the cognitive system; (5) cognition is for action; (6) off-line cognition is body based. Of these, the first three and the fifth appear to be at least partially true, and their usefulness is best evaluated in terms of the range of their applicability. The fourth claim, I argue, is deeply problematic. The sixth claim has received the least attention in the literature on embodied cognition, but it may in fact be the best documented and most powerful of the six claims.

Animals↗
PubMed1993

Repetition priming and proper name processing. Do common names and proper names prime each other?

Three experiments are reported in which a repetition priming technique was used to investigate whether recognition of a person's surname which is also a known word (e.g. Baker) activates the lexical representation that mediates word recognition. Experiment 1 showed that a familiarity decision to familiar full names produced an effect of repetition priming on subsequent lexical decision to words that were presented in the initial task as surnames. Experiment 2 demonstrated that, conversely, a lexical decision primed subsequent familiarity decision to full names involving the same word. Experiment 3 showed that repeating the same decision during the initial and test phases did not produce a larger repetition priming effect than that obtained when the task at test differed from the prime task (name familiarity decision vs lexical decision or vice versa). The results are interpreted as support for the view that repetition priming is due to repeated activation of representations that are accessed by both common names and proper names.

Adult↗
PubMed1996

Cognitive performance effects of subcutaneous nicotine in smokers and never-smokers.

In a double-blind placebo-controlled crossover study the effects of two doses of subcutaneous nicotine and saline were compared on a range of performance measures in 18 abstaining smokers and 18 never-smokers. Each subject received two injections (40 min apart) of saline, 0.3 mg nicotine, or 0.6 mg nicotine in a balanced order over three sessions. Performance was assessed before and after the injections on nine tests [news recall, Sternberg memory task, finger tapping, logical reasoning, rapid visual information processing (RVIP), long-term word recognition, digit recall, Stroop test, and critical flicker fusion threshold]. In the abstinent smokers, nicotine produced significantly faster correct responses on the logical reasoning test, more target hits, faster reaction times and improved sensitivity on the RVIP task, and more correct responses on word recognition. In never-smokers, nicotine produced faster reaction times on the RVIP and digit-recall tasks, although in the latter case this was at the expense of fewer correct responses. There were no significant differences between the two groups' responses to nicotine but smokers performed worse than never-smokers prior to injections, even controlling for background characteristics. These results are consistent with other recent research suggesting a primary effect of nicotine in enhancing cognitive performance.

Adult↗