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PubMed1992

ROENTGEN: case-based reasoning and radiation therapy planning.

ROENTGEN is a design assistant for radiation therapy planning which uses case-based reasoning, an artificial intelligence technique. It learns both from specific problem-solving experiences and from direct instruction from the user. The first sort of learning is the normal case-based method of storing problem solutions so that they can be reused. The second sort is necessary because ROENTGEN does not, initially, have an internal model of the physics of its problem domain. This dependence on explicit user instruction brings to the forefront representational questions regarding indexing, failure definition, failure explanation and repair. This paper presents the techniques used by ROENTGEN in its knowledge acquisition and design activities.

Artificial Intelligence↗
PubMedDate not supplied

Role of the frontal lobes in implicit and explicit retrieval tasks.

While the role of the frontal lobes in explicit retrieval tasks is well supported, the findings for implicit tasks are less conclusive. We investigated the role of the frontal lobes in perceptual and conceptual implicit priming. Three memory paradigms were given under both implicit and explicit retrieval instructions, using word fragment completion, picture fragment completion and category exemplar generation. Three groups of individuals with frontal lesions were compared to normal controls: Left dorsolateral lesions (n = 5), right dorsolateral lesions (n = 4), and medial lesions (n = 9). Word fragment completion priming was impaired by left dorsolateral lesions, with other priming tests unaffected by any lesion. Explicit performance showed a different pattern, with category exemplar cued recall impaired by left dorsolateral and medial lesions. These findings support the role of the frontal lobes in both implicit and explicit retrieval mechanisms under certain conditions requiring strategy application or lexical retrieval.

Adult↗
PubMed2001

Is position "special" in visual attention? Evidence that top-down processes guide visual selection.

The role of spatial position in selective visual processing has been the source of recent debate. Experiments by Tsal and Lavie (1988) and van der Heijden et al. (1996) have been designed to establish the status of position in visual selection. Tsal and Lavie found that observers tend to select letters from a briefly presented array according to position. Using the same paradigm, van der Heijden et al. found that observers tend to select according to colour, except under conditions of low contrast and unrestricted eye movements. The present study attempted to reconcile these findings by exploring the influence of top-down processes (task instructions) while explicitly controlling for eye movements. Experiment 1 demonstrated there was no inherent selection bias for stimuli similar to those used by van der Heijden et al., suggesting that the tendency to select according to colour found by van der Heijden et al. was due to task demands. Experiment 2 further established the role of top-down factors by replicating the results of van der Heijden et al. with our stimuli. Experiment 3 demonstrated that selection can be switched from colour to position by changing the demands of the task. These results suggest that selection may be accounted for by task demands (e.g., instructions) with no priority access for position information.

Analysis of Variance↗
PubMed2004

A mechanism of implicit lexicalized phonological recoding used concurrently with underdeveloped explicit letter-sound skills in both precocious and normal reading development.

These are findings of theoretical interest from: (i) follow-up of a case study of a precocious reader; and (ii) normally developing readers who served as comparison groups. The precocious reader was first reported when 2-3 years of age (Cognition 74 (2000) 177). From 3 to 7 years of age her precocious reading development continued, her word reading accuracy increasing from the 8- to the 16-year-level, although her phonemic awareness skills remained underdeveloped relative to word reading. Nonword reading continued to develop rapidly. Her word reading, however, was more than phonological recoding. At 5 years of age, in comparison with reading-level matched normal 11-year-olds she exhibited strong effects of semantic characteristics of words and evidence of well-specified lexical orthographic representations. In common with normal comparison 11-year-olds, who had not received instruction in explicit phonics, her explicit letter-sound skills were underdeveloped but she possessed high speed and accuracy in nonword reading, a result most theories of the acquisition of reading fail to explain. Her responses to irregularly spelt nonwords indicated higher proficiency than the 11-year-olds in acquiring lexical orthographic representations not predictable from prior phonological recoding knowledge. It is considered that this proficiency contributes to an explanation of her precocious reading development. A mechanism of implicit lexicalized phonological recoding is involved which explains the dissociation of skills in both the precocious reader and normally developing readers.

Analysis of Variance↗
PubMed1995

A comparison of two psychological treatments for bulimia nervosa: implications for models of maintenance.

In an effort to elucidate the role of cognitive factors in the maintenance of bulimia nervosa, the efficacy of two psychological treatments was examined in a randomised control trial: cognitive behaviour therapy in the absence of explicit exposure instructions was compared with exposure and response prevention treatment in the absence of cognitive restructuring procedures. In the short term both treatments were successful at effecting substantial improvement in both the specific and the non-specific psychopathology of the disorder. However, at a one year follow up, whilst improvements were well maintained for those who had received the cognitive-behavioural treatment, virtually all of those who had responded to the purely behavioural treatment had relapsed. This provides some support for the cognitive model of the maintenance of bulimia nervosa. Nevertheless, the two treatment groups could not be distinguished on post-treatment measures of cognitive disturbance and neither was it the case that residual levels of cognitive disturbance, as assessed, predicted relapse. This may suggest that the level at which the necessary cognitive change takes place may not be accessible by conventional assessment procedures.

Adolescent↗
PubMed1992

Event-related potential sensitivity to acoustic and semantic properties of terminal words in sentences.

This experiment was concerned with the effects of phonologically correct masking on the electrophysiological responses to terminal words of spoken sentences differing in contextual constraint. Two event-related potential (ERP) components, the N400 and N200, were recorded to the terminal words of high and low constraint sentences in four conditions. In the Control condition, subjects (Ss) simply attended to the sentences with no explicit task instructions. In the Semantic condition, Ss were required to listen to the stimuli in order to make semantic judgements about the terminal word of each sentence. The Control+Masking condition was identical to the Control condition except for the simultaneous presentation of a masking stimulus. The Semantic+Masking condition had Ss listening to sentences in the presence of masking with the task of making semantic judgements about the terminal word of each sentence. ERPs were recorded from Fz, Cz, Pz, T3, and T4 in 10 subjects. Amplitudes of both the N200 and the N400 were sensitive to contextual constraint with larger responses elicited by the terminal words of low constraint sentences. In addition to demonstrating the co-occurrence of the N200 and N400, this experiment highlighted a functional separation between the two components. Masking had no statistically significant effect on N200 latency but N400 latency was delayed in the masked conditions relative to those in the unmasked conditions. It is proposed that the N200 and N400 are manifestations of two different processes; the N200 reflects the acoustic/phonological processing of the terminal word while the N400 reflects the cognitive/linguistic processing. The relationship between the N200 recorded in this experiment and the discrimination N200 is discussed.

Adolescent↗
PubMedDate not supplied

Late event-related potential changes in alcoholics.

The P3 component of the event-related potential (ERP) was recorded during a Go/No-Go task from 42 alcoholic subjects, abstinent for 11-63 days, and 66 normal adult volunteers. In two different tasks, ERPs were elicited by visually presented words which provided explicit response instructions to Go (PUSH) or No-Go (WAIT). In the Noise Task, half of both Go and No-Go stimuli were degraded with ampersands (&P&U&S&H&, &W&A&I&T&). In the Probability Task, the probability of the Go stimulus was 25% and No-Go 75% on one run and the proportion reversed on another run. For both tasks, the amplitude of alcoholics' P3 was smaller than that of controls to the Go but not to the No-Go stimulus. There was a similar, but less pronounced trend for P3 latency to be delayed in alcoholic subjects for the Go, but not No-Go stimuli for the Noise Task. The P3 changes in alcoholics are consistent with those seen in several disease states which produce cognitive impairment.

Adult↗
PubMed2004

Awareness of muscular force during movement production: an fMRI study.

Awareness of the muscular forces we produce during voluntary movement must be distinguished from awareness of motor outcome itself. Indeed, there is no univocal relationship between produced muscle force and movement outcome because of external forces. In the present study, we performed a functional magnetic resonance imaging study to investigate the neural bases underlying the awareness we can have of the muscular forces we put into our voluntary movements. In reference conditions, subjects made rhythmical hand movements and knew they had to reproduce, in a subsequent condition in which the resistance to the movement was increased, either their muscular forces or their kinematics. The idea behind this (well established) reproduction paradigm is that, after an explicit verbal instruction, subjects can only reproduce what they are aware off. The main contrast, that is, between the condition during which the subjects had to gain awareness of their muscular forces and that during which they had to gain awareness of their kinematics (conditions in which the actual motor output was similar), shows that gaining awareness about muscular forces exerted during movement execution makes much higher demands on many brain structures, in particular posterior insula, primary sensorimotor areas and associative somatosensory areas. This indicates the important role of somesthetic information processing in awareness of produced muscular force. Therefore, the often-heard presumption that muscle force sense might be based on the outgoing motor command is not confirmed by the present results.

Adolescent↗
PubMed1987

Major ambulatory surgery of the orthopedic patient.

Orthopedic procedures that have been performed satisfactorily in an ambulatory setting are described. Ambulatory orthopedic surgery involves the same principles as inpatient orthopedic surgery. Explicit postoperative instructions to the patient and family member and the postoperative dressing are two factors of great importance in the ambulatory unit.

Ambulatory Surgical Procedures↗
PubMed1988

Data-driven and conceptually driven processes in partial-word identification and recognition.

Three experiments examined priming in partial-word identification (Warrington & Weiskrantz, 1968) and its relation to recognition memory. The results showed that changes in modality of presentation between study and test reduced performance on both identification and recognition. In contrast, changes in elaborative processing enhanced recognition but had no effect on identification. Furthermore, when explicit memory instructions were given, identification was changed to a cued recall test and was consequently affected by elaborative processing. We also found that the time course of forgetting in priming was different from that in recognition; priming in identification did not change over a 24-hr interval, whereas recognition declined rapidly during this interval. Overall, these results suggest that identification relies primarily on data-driven processing, whereas recognition can rely on both data-driven and conceptually driven processing.

Adult↗
PubMed2005

Multimodal homesickness prevention in boys spending 2 weeks at a residential summer camp.

Homesickness is the distress or impairment caused by an actual or anticipated separation from home. It is characterized by preoccupying thoughts of home and attachment objects. In its severe form, homesickness is subjectively distressing and has clinically significant cognitive, emotional, and behavioral sequelae. This study provided 75 boys who ranged in age from 8 to 16 years and who were 1st-year campers at an overnight summer camp with an inexpensive, multimodal homesickness prevention package. Results suggest that combining environmental information, psychoeducation, social support, explicit coping instruction, caregiver education, practice time away from home, and surrogate caregiver training can reduce homesickness and associated behavior problems. These data support the theory that novelty reduction, attitudinal shifts, preseparation coping enhancement, and supportive social environments diminish the negative emotional intensity of homesickness.

Adaptation, Psychological↗
PubMed2005

Positive affect as implicit motivator: on the nonconscious operation of behavioral goals.

Recent research has revealed that nonconscious activation of desired behavioral states--or behavioral goals--promotes motivational activity to accomplish these states. Six studies demonstrate that this nonconscious operation of behavioral goals emerges if mental representations of specific behavioral states are associated with positive affect. In an evaluative-conditioning paradigm, unobtrusive linking of behavioral states to positive, as compared with neutral or negative, affect increased participants' wanting to accomplish these states. Furthermore, participants worked harder on tasks that were instrumental in attaining behavioral states when these states were implicitly linked to positive affect, thereby mimicking the effects on motivational behavior of preexisting individual wanting and explicit goal instructions to attain the states. Together, these results suggest that positive affect plays a key role in nonconscious goal pursuit. Implications for behavior-priming research are discussed.

Affect↗
PubMed2004

Multidimensional rule, unidimensional rule, and similarity strategies in categorization: event-related brain potential correlates.

Forty participants assigned artificial creatures to categories after explicit rule instruction or feedback alone. Stimuli were typical and atypical exemplars of 2 categories with independent prototypes, conflicting exemplars sharing features of both categories, and "Others" with only 1 or 2 features of the well-defined categories. Ten feedback-only participants spontaneously adopted a unidimensional rule; 10 used a multidimensional similarity strategy. Event-related potentials (ERPs) recorded during the transfer phase showed a commonality between multidimensional rule and similarity strategies in late frontal brain activity that differentiated both from unidimensional rule use. Multidimensional rule users alone showed an earlier prefrontal ERP effect that may reflect inhibition of responses based on similarity. The authors also discuss the role of declarative memory for features and exemplars.

Adult↗
PubMed1992

Age-related differences in memory as a function of imagery processing.

The effects of aging on imagery production and use--following the learning of concrete and abstract words--and their relations to subsequent memory performance were explored in 2 experiments. Both experiments demonstrated better free recall of concrete than of abstract words (the concreteness effect). Experiment 1 showed this superiority to be greater for young subjects only under explicit imagery instructions. Experiment 2 revealed that the advantage of concrete over abstract words reflects the use of differential imagery production. The results are discussed in terms of age differences in imagery utilization and the effects of visual processing on recall.

Adult↗
PubMedDate not supplied

The effects of attention switching on encoding and retrieval of words in younger and older adults.

Two experiments examined the interaction between aging, attention switching, encoding process, and recognition memory using different versions of a cued attention switching paradigm. In Experiment 1, 30 younger and 35 older adults encoded words based on font color, meaning, or by explicit learning with a color response during performance of a choice-reaction time (RT) task. Attention switches were cued by means of stimulus location, and occurred on average every seven trials. In Experiment 2, attention switching was precued from a central fixation point and the number of critical switch trials was increased, occurring on average every four trials. Memory was assessed in both experiments by means of a forced-choice recognition task. Results indicated that, relative to color encoding, older adults benefited more than younger adults from semantic encoding, but less from explicit learning instructions. Attention switching disrupted encoding task performance of older adults more than that of younger adults, but recognition memory was generally unaffected. Results are discussed in light of theoretical models of aging memory that posit a role for executive control processing.

Adolescent↗
PubMed2006

Online maintenance of sensory and motor representations: effects on corticospinal excitability.

Flexible behavior requires the ability to delay a response until it is appropriate. This can be achieved by holding either a sensory or a motor representation online. Here we assess whether maintenance of sensory or motor material drives the motor system to different functional states, as indexed by alterations of corticospinal excitability. We used single-pulse TMS to measure corticospinal excitability evoked during the delay period of a novel paradigm in which task contingencies, rather than explicit verbal instructions, induced participants to use either sensory or motor codes to solve a delay-nonmatch-to-sample (DNMS) task. This approach allowed us to probe the state of the motor system while the participants were retaining either sensory or motor codes to cross the delay period, rather than the control of short-term storage driven by verbal instructions. When participants could prepare the movement in advance (preparation trials), the excitability of the motor cortex contralateral to the moving hand increased, whereas the excitability of the ipsilateral motor cortex decreased. The increase in excitability was confined to the prime mover, whereas the decrease in excitability extended to cortical territories controlling muscles unrelated to the response. Crucially, these changes in excitability were evoked only during preparation trials and not during trials in which subjects needed to maintain sensory items online (memory trials). We infer that short-term storage of sensory information and preparation of motor responses have differential and specific access to the output stage of the motor system.

Adult↗
PubMedDate not supplied

Early reading for low-SES minority language children: an attempt to 'catch them before they fall'.

Minority language and low socioeconomic status (SES) students are at high risk for language and learning disabilities. In an attempt to 'catch them before they fall', an early reading project was initiated in four kindergarten classes, in a low-SES bilingual school (English/French as a second language), where minority language children form a majority. The project included: (1) teaching reading and writing to kindergarten students, and outcome research: individual pre- and post-treatment assessment using a computer software to measure phonological processing and decoding skills; (2) reading testing of grade 1 students, graduates of traditional kindergartens with no explicit reading instruction programs. Statistical analyses of the pre- and post-tests showed that in only 9 weeks the kindergarten students were able to learn phonological skills critical to the reading process. By contrast, a significant number of the grade 1 students, all graduates of a traditional kindergarten, showed serious reading lags on a group reading test, indicating that early reading instruction is justifiable for this high-risk student population.

Age Factors↗
PubMed1993

Improvements in the English syntax of deaf college students.

The present study was designed to determine whether prelingually deaf students continue to improve in their knowledge of English syntax once they reach the college level. Students were assessed on their knowledge of nine English structures at the beginning and the end of the academic year. The results revealed significant improvement on all structures; however, students with lower general English proficiency improved to a significantly greater extent than students with higher general English proficiency. This suggests that deaf students with low proficiency might benefit from an increase in explicit grammar instruction. The results of this study are promising in that improved English syntax provides deaf students with more degree options and greater access to college-level reading materials.

Achievement↗