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PubMed2000

Keeping track: the function of the current state buffer.

The Current State Buffer has been proposed to account for our ability to keep track of significant stimuli in our immediate environment. The three experiments reported here were designed to test the independence of the Current State Buffer from the established components of Working Memory. Pre-schoolers were used in order to minimize the possible interference of other memory structures and complex strategies on the part of the subjects, thus allowing a cleaner test of the hypotheses. In the experiments, 180 pre-schoolers watched an Emu glove puppet tidy away toys into receptacles (the 'Tidy Emu Paradigm'), such that the number of pairings just exceeded their capacity for recall of the locations of toys in receptacles. We take this task to be a prototypical visuospatial Working Memory task. In the Object condition of Experiment 1, a Teddy was an object and was tidied away with the other toys. In the Character condition the Teddy was an animated character who interacted with the children and then went to sleep in one of the receptacles. Where Teddy was a character, all children remembered his location even though they had not been asked to; when he was an object only half of the children were correct despite explicit instructions to remember. More crucially, the location of the other toys was better recalled for children in the Character condition than those in the Object condition. These data are taken as evidence for the independence of the Current State Buffer from the Visuospatial Sketchpad. Other explanations, such as a von Restorff effect, are considered, and Experiments 2 and 3 test and reject these as possibilities.

Child, Preschool↗
PubMed1999

Contour determination for ovate pontics.

The ovate pontic was initially described in 1933, but was only recently considered clinically acceptable. Historically, there has been resistance to ovate pontics, but this resistance lacks scientific and biologic evidence to justify rejection. Explicit instructions are mandatory for predictable results from dental laboratories. This article describes a method for communicating exact dimensions for an ovate pontic that was previously contoured for a patient in a provisional restoration to ensure clinical and histologic success. Polyvinyl siloxane putty is suggested as a matrix material for the predetermined contour. An esthetic and functional restoration will result when these materials and procedures are used in an appropriate sequence.

Attitude of Health Personnel↗
PubMed1998

Delayed recognition memory in infants and adults as revealed by event-related potentials.

The present study sought to compare adult and infant ERP responses in analogous tests of visual recognition memory. Adults were tested under two test conditions, in which they were given either explicit instructions to respond to a previously-seen stimulus, or no instructions. Testing in both conditions took place after either a 1- or 5-min delay between familiarization and test. Eight-month-old infants were tested under the same 'passive' (no instruction) conditions as adults. ERP morphology differed across age groups. Adults evinced a P300 that was larger under 'active' as compared to 'passive' test conditions, and a late positive slow wave response that was greater to novel than familiar stimuli. There was no evidence in infants of a P300, although infants did demonstrate a late positive slow wave that was greater to familiar than to novel stimuli. Parallels between the infant and adult findings are discussed and in particular, whether the infant slow wave response is the precursor to the adult P300.

Adolescent↗
PubMed1998

Evaluation of compliance with a computerized protocol: weaning from mechanical ventilator support using pressure support.

STUDY OBJECTIVES: To use a computerized consultation system to evaluate the feasibility of a mechanical ventilator weaning protocol which used the rapid shallow breathing index to guide adjustments in pressure support. A program to monitor user compliance and reasons for noncompliance was built into the computerized consultation system. METHODS: A total of nine critically ill patients (ten weaning episodes) were enrolled in the protocol. The respiratory therapists performed routine computer charting in the electronic database. They accepted or declined the explicit instructions generated by the computerized protocol and displayed on the bedside terminal. The consultation program monitored whether accepted instructions were implemented by the user. RESULTS: Patient's therapy was controlled by protocol for a total of 1075 h (mean 108 h, range 4 to 339 h) and 94.8% (1321/1394) of instructions were followed by the clinical staff. Of the 42 instructions clinical staff refused to follow, 23 (55%) were extubation instructions. There were 52 (3.7%) incorrect instructions generated with 24 software errors, 21 errors in underlying logic, and seven user misunderstanding errors. CONCLUSIONS: A high level of user compliance with this protocol was achieved. The methods described herein to monitor compliance and reasons for noncompliance within a protocol are reusable in the domain of mechanical ventilation and possibly in other domains.

Evaluation Studies as Topic↗
PubMed2002

A teamwork model to promote patient safety in critical care.

To create a safe health care system, providers must understand teamwork as a complementary relationship of interdependence. Continuing efforts to adopt the aviation model will enable health care providers to examine the role of human performance factors related to fatigue, leadership, and communication among all providers. The aviation model provides a basis for designing teamwork programs to reduce error and introduces human factor principles and key skills to be learned. Health care providers need explicit instruction in communication and teamwork rather than learning by trial and error, which can instill unintended values, attitudes, and behaviors. The growing research base continues to examine the problem of health care safety and to test the most effective team training approaches. What is the most effective pattern and timing of communication among providers? What system level changes are needed in the critical care area to improve communication through teamwork and thus create a safer health care system? What are potential points of error in the daily operation that could be alleviated through effective teamwork? Continuing to test the model will ultimately change patient safety.

Communication↗
PubMed2003

Perception and judgement of physical causality involve different brain structures.

One basic type of 'mechanical' causality is that which occurs between physical objects. Subjects were presented with mechanically causal events (ball collides with and causes movement of another ball) or two non-causal events (a ball either passes underneath another ball, or rolls across the screen and changes colour). We investigated which brain regions exhibit increased activity during the judgement of causality ('judged causality') as compared with judgement of movement direction ('perceived causality'). We show an increase of medial frontal cortex activity when subjects were explicitly instructed to search for causality. Moreover, this increase was specifically associated with the search for causality and not with the perception of causality because the signal increase occurs whatever the nature of the stimulus (causal or non causal). Our study provides evidence for brain regions involved in a conscious level of inference about the presence of causality.

Adult↗
PubMed2003

Visual short-term memory load affects sensory processing of irrelevant sounds in human auditory cortex.

We used whole-head magnetoencephalography (MEG) to investigate neural activity in human auditory cortex elicited by irrelevant tones while the subjects were engaged in a short-term memory task presented in the visual modality. As compared to a no-memory-task condition, memory load enhanced the amplitude of the auditory N1m response. In addition, the N1m amplitude depended on the phase of the memory task, with larger response amplitudes observed during encoding than retention. Further, these amplitude modulations were accompanied by anterior-posterior shifts in N1m source locations. The results show that a memory task for visually presented stimuli alters sensory processing in human auditory cortex, even when subjects are explicitly instructed to ignore any auditory stimuli. Thus, it appears that task demands requiring attentional allocation and short-term memory result in interaction across visual and auditory brain areas carrying out the processing of stimulus features.

Acoustic Stimulation↗
PubMed2003

Finger interactions studied with transcranial magnetic stimulation during multi-finger force production tasks.

OBJECTIVE: We used transcranial magnetic stimulation (TMS) to investigate interactions among neuromuscular complexes involved in force production by individual fingers of a hand during single- and multi-finger tasks. METHODS: Subjects were asked to press with the fingertips at various levels of force using different finger combinations. TMS was applied over the M1 cortical hand area during constant force production. TMS-induced increments in fingertip forces were analyzed, as well as motor evoked potentials (MEPs) in flexor digitorum superficialis. RESULTS: Both MEP size and individual force increments had inverted U-shaped dependences on the background force (peak responses were seen at about 50% of the maximal force). Similar relationships were obtained when subjects were asked to produce different forces with the same finger combination or the same total force with different finger combinations. The relationships were similar when the force was produced by explicitly instructed fingers or by other fingers of the hand. Effects of TMS on the force of a finger showed a strong dependence on the background force produced by this finger and minimal or no dependence on forces produced by other fingers of the hand. CONCLUSIONS: Overall, TMS applied over M1 revealed little interaction among fingers. This supports the notion of digit-specific compartments in multi-digit extrinsic muscles of the hand and suggests that these compartments possess a high degree of physiological independence.

Adult↗
PubMed2006

Risk perception and acceptance--one process or two? The impact of aspirations on perceived risk and preferences.

The experiments discussed here are aimed at determining whether risk perception and risk acceptance are two distinct psychological processes. This study is motivated by the idea of a double-criterion model of choice. In particular, in line with risk-value (R-V) models, in which risk is treated as a primitive, it is tested whether risk is independent of aspirations and whether preferences depend on aspirations. In two experiments, 305 university students were presented with pairs of risky projects and were asked to compare their riskiness and select one. The aspiration level, defined as the target return on the project, was set through an explicit instruction. In Experiment 1, a within-subject designwas applied, and thus aspirations were set at two different levels. In Experiment 2, with a between-subject design, two different aspiration levels were set for each group. The results indicate that risk ordering is insensitive to changes in aspirations, but preferences are sensitive to those changes. This supports distinctness of risk perception and risk acceptance. The findings are discussed in terms of the CPT and SP/A models and the R-V approach. It appears that double-criterion models provide better and psychologically sounder predictions of subjects' preferences.

Aspirations, Psychological↗
PubMed1984

Considering the opposite: a corrective strategy for social judgment.

It is proposed that several biases in social judgment result from a failure--first noted by Francis Bacon--to consider possibilities at odds with beliefs and perceptions of the moment. Individuals who are induced to consider the opposite, therefore, should display less bias in social judgment. In two separate but conceptually parallel experiments, this reasoning was applied to two domains--biased assimilation of new evidence on social issues and biased hypothesis testing of personality impressions. Subjects were induced to consider the opposite in two ways: through explicit instructions to do so and through stimulus materials that made opposite possibilities more salient. In both experiments the induction of a consider-the-opposite strategy had greater corrective effect than more demand-laden alternative instructions to be as fair and unbiased as possible. The results are viewed as consistent with previous research on perseverance, hindsight, and logical problem solving, and are thought to suggest an effective method of retraining social judgment.

Attitude↗
PubMed2001

The effects of social category norms and stereotypes on explanations for intergroup differences.

A 2-stage model of the construction of explanations for differences between groups is presented. Category norms affect which of 2 groups becomes "the effect to be explained," and stereotypes shape attributions about that group. In 3 experiments, 288 participants wrote explanations for differences between gay and straight men. Explanations focused on gay men who were also judged to have more mutable attributes. However, these effects were not correlated. Participants focused explanations on straight men when explicitly instructed to do so (Experiment 1). Explanations focused on both groups equally when the gay men constituted the numerically larger sample, when gay men were more typical of the overarching category (i.e., people with AIDS) than straight men, or when more straight men were described as performing the behavior (Experiment 2). Stereotype-consistent information prompted more essentialist references and fewer reconstructive references to gay men than did stereotype-inconsistent information (Experiment 3). The relevance of this model for theories of norms, stereotypes, and for the conduct of social science is discussed.

Adult↗
PubMed2002

Roles of salience and strategy in conjunction search.

In some cases, the search for a conjunction target proceeds through the smaller group of elements in a display, whereas in others, search is limited to those elements that share a particular feature with the target. In 6 experiments, participants searched for a conjunction target among displays consisting of various proportions of 2 distractor types. Smaller-group search was more prevalent than target-feature search with denser displays and with features that were highly discriminable. Explicit instructions to limit search to a specific feature affected performance only when the discriminability of the guiding feature was much greater than the other target feature. Together, these experiments show that bottom-up factors have more influence in guiding conjunction searches than previously thought.

Analysis of Variance↗
PubMed1988

Frequency encoding of token and type information.

Two experiments examined how attention to stimulus attributes affects knowledge of frequency of occurrence. In Experiment 1, orienting tasks were used to direct subjects' attention to either the category membership or the initial letters of words. In Experiment 2, subjects' attention to words, category membership, and initial letters was directed with explicit instructions. The results of these two experiments suggest that attention to specific stimulus attributes may be necessary to initiate the encoding of frequency information. We discuss the implications of these results for claims that the encoding of frequency of occurrence is automatic.

Attention↗
PubMed1992

Comprehension strategies in the development of a mental model.

It is generally assumed that the comprehension strategy used in the development of a mental model for narrative texts focuses on information that is relevant to the protagonist. Experiments 1a and 1b confirmed that readers remain sensitive to the location of the protagonist even when strategies based on text-base level representations predict this information should not be active. Experiments 2 and 3 tested the stronger claim that readers adopt the perspective of the protagonist. Ss did not notice information that was contradictory from the perspective of the protagonist unless explicitly instructed to adopt that perspective. It was concluded that, at the level of the mental model, readers focus on information relevant to the protagonist but that they do not adopt the perspective of the protagonist unless characteristics of the text induce such a strategy.

Adult↗
PubMed2001

Revealing hidden covariation detection: evidence for implicit abstraction at study.

Four experiments in the brain scans paradigm (P. Lewicki, T. Hill, & I. Sasaki, 1989) investigated hidden covariation detection (HCD). In Experiment 1 HCD was found in an implicit- but not in an explicit-instruction group. In Experiment 2 HCD was impaired by nonholistic perception of stimuli but not by divided attention. In Experiment 3 HCD was eliminated by interspersing stimuli that deviated from the critical covariation. In Experiment 4 a transfer procedure was used. HCD was found with dissimilar test stimuli that preserved the covariation but was almost eliminated with similar stimuli that were neutral as to the covariation. Awareness was assessed both by objective and subjective tests in all experiments. Results suggest that HCD is an effect of implicit rule abstraction and that similarity processing plays only a minor role. HCD might be suppressed by intentional search strategies that induce inappropriate aggregation of stimulus information.

Adult↗
PubMed2002

Statistical learning of higher-order temporal structure from visual shape sequences.

In 3 experiments, the authors investigated the ability of observers to extract the probabilities of successive shape co-occurrences during passive viewing. Participants became sensitive to several temporal-order statistics, both rapidly and with no overt task or explicit instructions. Sequences of shapes presented during familiarization were distinguished from novel sequences of familiar shapes, as well as from shape sequences that were seen during familiarization but less frequently than other shape sequences, demonstrating at least the extraction of joint probabilities of 2 consecutive shapes. When joint probabilities did not differ, another higher-order statistic (conditional probability) was automatically computed, thereby allowing participants to predict the temporal order of shapes. Results of a single-shape test documented that lower-order statistics were retained during the extraction of higher-order statistics. These results suggest that observers automatically extract multiple statistics of temporal events that are suitable for efficient associative learning of new temporal features.

Analysis of Variance↗
PubMed2006

The importance of gesture in children's spatial reasoning.

On average, men outperform women on mental rotation tasks. Even boys as young as 4 1/2 perform better than girls on simplified spatial transformation tasks. The goal of our study was to explore ways of improving 5-year-olds' performance on a spatial transformation task and to examine the strategies children use to solve this task. We found that boys performed better than girls before training and that both boys and girls improved with training, whether they were given explicit instruction or just practice. Regardless of training condition, the more children gestured about moving the pieces when asked to explain how they solved the spatial transformation task, the better they performed on the task, with boys gesturing about movement significantly more (and performing better) than girls. Gesture thus provides useful information about children's spatial strategies, raising the possibility that gesture training may be particularly effective in improving children's mental rotation skills.

Child↗
PubMed2003

Implicit, long-term spatial contextual memory.

Learning and memory of novel spatial configurations aids behaviors such as visual search through an implicit process called contextual cuing (M. M. Chun & Y. Jiang, 1998). The present study provides rigorous tests of the implicit nature ofcontextual cuing. Experiment 1 used a recognition test that closely matched the learning task, confirming that memory traces of predictive spatial context were not accessible to conscious retrieval. Experiment 2 gave explicit instructions to encode visual context during learning, but learning was not improved and conscious memory remained undetectable. Experiment 3 illustrates that memory traces for spatial context may persist for at least 1 week, suggesting along-term component of contextual cuing. These experiments indicate that the learning and memory of spatial context in the contextual cuing task are indeed implicit. The results have implications for understanding the neural substrate of spatial contextual learning, which may depend on an intact medial temporal lobe system that includes the hippocampus (Mi. M. Chun & E. A. Phelps, 1999).

Association Learning↗