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PubMed2002

The origin of conditional logic: does a cheater detection module exist?

The domain-specific hypothesis of L. Cosmides (1989) and L. Cosmides and J. Tooby (1989, 1992) positing that conditional logic has its origin in the evolution of social exchange and in the detection of potential cheaters was tested against a more domain-general hypothesis positing that adult reasoning is logical and that errors in conditional reasoning arise from misunderstandings, not from a lack of logicality. The results of 5 experiments with undergraduate students (n = 682 for Experiments 1-4; n = 188 for Experiment 5), which involved a series of selection tasks that yielded specific predictions about participant performance, were not consistent with the cheater detection hypothesis. Findings supported the misunderstandings hypothesis and imply that adults possess general-purpose logical competence versus domain-specific modules.

Adult↗
PubMed2004

Mental representation of logical connectives.

Logical connectives, such as "AND", "OR", "IF. THEN", and "IF AND ONLY IF" are ubiquitous in both language and cognition; however, reasoning with logical connectives is error-prone. We argue that some of these errors may stem from people's tendency to minimize the number of possibilities compatible with logical connectives and to construct a "minimalist" one-possibility representation. As a result, connectives denoting a single possibility (e.g., conjunctions) are likely to be represented correctly, whereas connectives denoting multiple possibilities (e.g., disjunctions or conditionals) are likely to be erroneously represented as conjunctions. These predictions were tested and confirmed in three experiments using different paradigms. In Experiment 1, participants were presented with a multiple-choice task and asked to select all and only those possibilities that would indicate that compound verbal propositions were true versus false. In Experiment 2, a somewhat similar task was used, except that participants were asked later to perform a cued recall of verbal propositions. Finally, Experiment 3 used an old/new recognition paradigm to examine participants' ability to accurately recognize different logical connectives. The results of the three experiments are discussed in relation to theories of representation of possibilities and theories of reasoning.

Adult↗
PubMed1996

Fuzzy logic control of inspired isoflurane and oxygen concentrations using minimal flow anaesthesia.

In order to evaluate the performance of feedback fuzzy logic control of inspired oxygen and isoflurane concentrations, we studied 30 patients undergoing discectomy for lumbar (n = 26) or cervical (n = 4) disc herniation. Patients were allocated random to one of two groups: a standard group (n = 15) with low flow anaesthesia (1.2-1.3 litre min-1) and manual control of gas concentrations; and a fuzzy group (n = 15) with minimal flow (0.5 litre min-1) and fuzzy logic feedback control of gas concentrations. Fuzzy logic control achieved and maintained very accurately the desired isoflurane concentration. Oxygen concentration was controlled more precisely than in the standard group. Delivery and costs of oxygen and nitrous oxide were significantly lower in the fuzzy group (P < 0.01). Accumulation of foreign gases was observed in one patient during low flow and in 11 patients during minimal flow anaesthesia. In conclusion, fuzzy logic control of inspired oxygen and isoflurane concentration during minimal flow anaesthesia was reliable and reduced anaesthetic gas delivery and costs.

Adult↗
PubMed1985

The logical status of brain death criteria.

This article is an attempt to clarify a confusion in the brain death literature between logical sufficiency/necessity and natural sufficiency/necessity. We focus on arguments that draw conclusions regarding empirical matters of fact from conceptual or ontological definitions. Specifically, we critically analyze arguments by Tom Tomlinson and Michael B. Green and Daniel Wikler, which, respectively, confuse logical and natural sufficiency and logical and natural necessity. Our own conclusion is that it is especially important in discussing the brain death issue to observe the distinction between logical and natural sufficiency/necessity in a strict fashion.

Brain Death↗
PubMedDate not supplied

Automated sensory nerve conduction testing using fuzzy logic.

Nerve conduction studies continue to be an important tool in the evaluation of peripheral nerve disorders but have come under increased scrutiny because of heightened cost control in health care service delivery. In selected clinical settings, automated nerve conduction studies may be a useful clinical tool replacing conventional testing, but existing instruments are limited and have not generally been accepted into clinical practice. Further advancements in nerve conduction automation may be possible by incorporating expert system approaches into nerve conduction measurement and control algorithms. Using fuzzy logic techniques to duplicate the reasoning strategies of experienced electrodiagnostic clinicians, a software controller was developed to automatically perform sensory nerve conduction studies. The fuzzy logic system successfully performed 88% of 97 sensory studies in a mixed group of normal and patient populations. Sensory nerve action potential latency and amplitude measures obtained with automated testing were the same as determined by clinicians. Failures were related to design limitations of the controller, noise, and artifact. The high negative predictive value and sensitivity of fuzzy logic based testing suggest that its utility is in minimizing the need for unnecessary conventional electrodiagnostic studies in patients with normal nerve function. Fuzzy logic appears to be a useful approach to nerve conduction automation that can model expert reasoning and judgment.

Action Potentials↗
PubMed1989

The influence of logical positivism on nursing practice.

While logical positivism has been said to have had major influence on the development of nursing theory, whether this influence pervades other aspects of the discipline has not been discussed. One central aspect of logical positivism, the verificationist perspective, was used to examine texts, curricular guides and standards of practice that guided nursing practice in the decades in which logical positivism had influence on nursing theory construction. This review of the literature does not support the influence of logical positivism, as exemplified by the verificationist perspective, on nursing practice guidelines.

Curriculum↗
PubMed2000

Shifting from the perceptual brain to the logical brain: the neural impact of cognitive inhibition training.

What happens in the human brain when the mind has to inhibit a perceptual process in order to activate a logical reasoning process? Here, we use functional imaging to show the networks of brain areas involved in a deductive logic task performed twice by the same subjects, first with a perceptual bias and then with a logical response following bias-inhibition training. The main finding is a striking shift in the cortical anatomy of reasoning from the posterior part of the brain (the ventral and dorsal pathways) to a left-prefrontal network including the middle-frontal gyrus, Broca's area, the anterior insula, and the pre-SMA. This result indicates that such brain shifting is an essential element for human access to logical thinking.

Adult↗
PubMed1999

Automatic control of pressure support mechanical ventilation using fuzzy logic.

There is currently no universally accepted approach to weaning patients from mechanical ventilation, but there is clearly a feeling within the medical community that it may be possible to formulate the weaning process algorithmically in some manner. Fuzzy logic seems suited this task because of the way it so naturally represents the subjective human notions employed in much of medical decision-making. The purpose of the present study was to develop a fuzzy logic algorithm for controlling pressure support ventilation in patients in the intensive care unit, utilizing measurements of heart rate, tidal volume, breathing frequency, and arterial oxygen saturation. In this report we describe the fuzzy logic algorithm, and demonstrate its use retrospectively in 13 patients with severe chronic obstructive pulmonary disease, by comparing the decisions made by the algorithm with what actually transpired. The fuzzy logic recommendations agreed with the status quo to within 2 cm H(2)O an average of 76% of the time, and to within 4 cm H(2)O an average of 88% of the time (although in most of these instances no medical decisions were taken as to whether or not to change the level of ventilatory support). We also compared the predictions of our algorithm with those cases in which changes in pressure support level were actually made by an attending physician, and found that the physicians tended to reduce the support level somewhat more aggressively than the algorithm did. We conclude that our fuzzy algorithm has the potential to control the level of pressure support ventilation from ongoing measurements of a patient's vital signs.

Adult↗
PubMed2004

Two-year evaluation of the logic model for developing a psycho-oncology service.

OBJECTIVE: The objective of this study was to test whether reorganizing a psycho-oncology service in a planned and focused manner would maximize the achievement of coherent developmental goals. METHODS: The logic model, a strategic program development tool, was used in the context of a public psychiatry fellowship to analyze and plan the organizational objectives of a psycho-oncology service. To assess the efficacy of the logic model, a two-year prospective evaluation of the model's outcome measures was performed. RESULTS: The psycho-oncology service was systematically reorganized through use of the logic model. Qualitative and quantitative data identified the degree of goal achievement. Most of the short- and medium-term clinical, educational, and research goals, as measured by outcome measures, had been realized at the two-year point. CONCLUSIONS: The logic model facilitated the effective reorganization of a psycho-oncology program by analyzing the existing service, developing pertinent goals, and then measuring goal attainment. These findings will be useful to psychiatric services interested in rational program development and service delivery, especially in small and medium hospitals with limited resources.

Achievement↗
PubMed2005

When logic fails: implicit transitive inference in humans.

Transitive inference (TI) in animals (e.g., choosing A over C on the basis of knowing that A is better than B and B is better than C) has been interpreted by some as reflecting a declarative logical inference process. We invert this anthropomorphic interpretation by providing evidence that humans can exhibit TI-like behavior on the basis of simpler associative mechanisms that underlie many theories of animal learning. In this study, human participants were trained on a five-pair TI problem (A+B-, B+C-, C+D-, D+E-, E+F-) and, unlike in previous human TI studies, were prevented from becoming explicitly aware of the logical hierarchy, so they could not employ logical reasoning. They were then tested with three problems: B versus D, B versus E, and C versus E. Participants only reliably chose B over E, whereas the other test conditions yielded chance performance. This result is inconsistent with the use of logical reasoning and is instead consistent with an account developed to explain earlier TI studies with rats that found the same pattern of results. In this account, choice performance is based on differential associative strengths across the stimulus items that develop over training, despite equal overt reinforcement.

Awareness↗
PubMed2001

Conjunctive bias in memory representations of logical connectives.

The paper presents the conjunctive bias in memory-a novel phenomenon that helps to clarify representations of logical connectives. The conjunctive bias is a tendency toward more accurate recall and recognition of conjunctive forms than of forms based on other logical connectives and a tendency to recall and recognize other logical forms as if they were conjunctions. Three experiments, in which participants' memory representations associated with different logical connectives were examined, were conducted to test the conjunctive bias hypothesis. In Experiment 1, participants learned picture-proposition pairs involving either conjunctions or disjunctions and then had to recall each proposition when cued with its picture. In Experiments 2 and 3, recognition memory for conjunctions, disjunctions, and conditionals was examined with an old/new recognition procedure. The findings of these experiments provide evidence for the conjunctive bias. Furthermore, the results of Experiment 3 suggest that corjunctive bias is not simply a pragmatically caused preference for conjunctions. The discussion focuses on the implications of these findings for current theories of deductive reasoning.

Adult↗
PubMedDate not supplied

Improved sensitivity of fuzzy logic based tumor marker profiles for diagnosis of pancreatic carcinoma versus benign pancreatic disease.

BACKGROUND: The definite diagnosis of pancreatic tumors of unknown origin remains a clinical challenge. Imaging techniques may fail to differentiate malignant tumors from inflammation, especially in chronic pancreatitis. In a considerable number of cases, the definitive diagnosis needs laparotomy. Single tumor markers as CA 19-9 or CEA are of limited value in these cases because of their limited sensitivity and specificity. This study was performed to find out, whether a classification method based on fuzzy logic analysis of tumor marker profiles is feasible in patients with pancreatic carcinoma and benign pancreatic disease. PATIENTS AND METHODS: Tumor markers and other clinical and laboratory parameters of 74 consecutive patients, either with histologically proved pancreatic carcinoma (n = 43) or presumed benign pancreatic disease (n = 31) assessed by ultrasound, endoscopic retrograde pancreatography, or computed tomography were analysed in order to detect their diagnostic value in the multi-dimensional approach of fuzzy logic analysis. RESULTS: Given a specificity of 95%, sensitivity was considerably increased by the fuzzy logic method (83%) compared with the best single tumor marker CA 19-9 (65%). CA 19-9, CYFRA 21-1 and CA 15-3 gave the most considerable contributions to the classification system, whereas CEA, CA 125, CA 72-4, AFP, liver enzymes, lipase, amylase, bilirubin, and ferritin were of no or little value. CONCLUSIONS: Tumor marker profiles analysed with the fuzzy logic method may have an improved sensitivity compared with single standard tumor markers. The diagnostic efficacy should be proved in patients with pancreatic tumors of unknown origin.

Adult↗
PubMed1975

Effect of chronological age and mental age on the understanding of rules of logic.

The relative difficulty of understanding the logical rules of conjunction and disjunction was studied. Because rules of logic must be viewed in the context of the attributes of information to which they refer, three attribute dimensions were also investigated: (a) positive-negative, (b) quantitative-nonquantitative, and (c) concrete-abstract. A further issue relevant to this research was the effect of CA and MA on the understanding of rules of logic. Subjects included four groups, one group of children with average IQs, one learning-disability group, and two mentally handicapped groups. The learning disability group was matched with the average group on MA and CA. The older mentally handicapped group matched the aveage and learning-disability groups on MA. The younger mentally handicapped group matched the average and learning-disability groups for CA and the older mentally handicapped group for IQ. A test was constructed to assess rule and attribute understanding. Results indicated that all groups perfomed similarly on the concrete level. On the abstract level, the average group performed significantly higher than the other groups. The results support a developmental interpretation of rule learning which maintains that once logical rules are learned, attributes of information acquire meaning within the context of those rules.

Age Factors↗
PubMedDate not supplied

[The logic of differential diagnosis].

The methodological aspects of making a differential diagnosis have so far received little attention. The aim of the present study is therefore to analyze the logical structure of this phase of clinical procedure. It is commonly believed that making a differential diagnosis involves an inferential process through which the clinician first makes diagnostic hypotheses, rules out all these prospective hypotheses except for one, and then concludes that the one remaining hypothesis identifies the disease affecting the patient. Some authoritative scientific methodologists sustain that the logical mechanism leading to the rejection of a diagnostic hypothesis is the negation of the consequent, and is thus the falsification proposed by Popper as the fundamental inference in experimental science. In the present study it is therefore suggested that in making a differential diagnosis, clinicians utilize disjoined syllogism rather than a negation of the consequent. A description is given of the structures of the two types of disjoined syllogism, which are inclusive and exclusive. An in-depth analysis is made of the entire diagnostic-differential reasoning process, and the authors suggest that, on a logical plane, it consists of two distinct sequential inferences, one being an eliminative induction and the other an inclusive disjoined syllogism. Lastly, it is pointed out that, as in the clinic, perfect pathognomonic signs are rarely encountered, each inference leading to a rejection of a diagnostic hypothesis can never be apodictic, and can only lead to a probable conclusion. The confutation of diagnostic hypotheses thus appears to be based on the rule of the denial of inductive logic.

Diagnosis, Differential↗
PubMedDate not supplied

[Logical structure of the problem oriented clinical record. A combined Popper-Bayes approach].

The problem-oriented medical record is a tool whose correct compilation meets the requirements of the law as well as the need for continuing medical education within the logic of clinical decision making. The reading of the contents of a record allows people to evaluate the correspondence between the "thinking" and the "doing" of a doctor, as well the objectivity of the facts--that is, the truth related to the reasons for a patient's admission to hospital and the nature of his or her illness. To this aim, the authors suggest a structural logical iter in concordance with the lines of hypothetical-deductive epistemology, in contrast to inductive epistemology, as tradition has always suggested. The latter, in fact, proposes to start from singular observations and proceeding, by successive steps, towards a diagnosis. It thus neglects to take error into consideration, and therefore the differential diagnostic process, and ignores the fact that one cannot pass from single descriptions to universal (diagnostic) laws on the basis of logic. The process of falsification therefore plays a central role in the diagnostic procedure and thus in the construction of the medical record. This falsification process is centered, according to the most recent epistemology, on the logical schemes of Popper-Hempel and Bayes. The authors propose an integrated combination of both schemes to enable a correct approach to diagnostic hypothesis and to differential diagnosis, with their relevant legal, didactic and administrative repercussions.

Bayes Theorem↗
PubMed2002

Role grouping as an extension to the description logic of Ontylog, motivated by concept modeling in SNOMED.

Several clinical terminologies now utilize description logic to model the logical definitions of concepts. Recent editions of the Systematized Nomenclature of Medicine (SNOMED) have been developed using the description logic Ontylog. A significant design criterion for SNOMED is to keep concept expressions simple enough to be broadly usable by clinicians, while maintaining faithful representation of concept meaning. Motivated by this criterion, "role grouping" has been developed as an extension to the description logic Ontylog. This paper describes the problems that motivated the creation of role grouping, outlines the semantics of role grouping, illustrates the benefits of this construct with examples from SNOMED Clinical Terms, and provides an algorithm for determining normal forms for expressions involving role groups.

Algorithms↗
PubMedDate not supplied

Improved sensitivity in the diagnosis of gastro-intestinal tumors by fuzzy logic-based tumor marker profiles including the tumor M2-PK.

The aim of this study was to improve diagnostic efficiency in the detection of gastro-intestinal cancers by using fuzzy logic modeling in combination with a tumor marker panel (CEA, CA72-4, CA19-9) including Tumor M2-PK. In this prospective study histologically confirmed colorectal (n=247), esophageal (n=86) and gastric cancer (n=122) patients were investigated and compared to control (n=53) persons without any malignant diseases. Tumor M2-PK was measured in plasma with an ELISA (ScheBoBiotech, Germany); all other markers were measured in sera (Roche, Germany). At 95% specificity, tumor detection was possible by the best single marker in colorectal cancer patients in 48% (Tumor M2-PK), in gastric cancers in 61% (CA72-4) and in esophageal cancers in 56% (Tumor M2-PK). A fuzzy logic rule-based system employing a tumor marker panel increased sensitivity significantly in colorectal cancers (p<0. 001) to 63% (Tumor M2-PK and CEA), in gastric cancers (p<0.001) to 81% (Tumor M2-PK and CA 72-4) and in esophageal cancers (p<0.02) to 74% (Tumor M2-PK and CA72-4). Adding a third marker further improved the sensitivity only marginally. Fuzzy logic analysis has proven to be more powerful than measurement of single markers alone or combinations using multiple logistic regression analysis of the markers. Therefore, with the fuzzy logic method and a tumor marker panel (including Tumor M2-PK), a new diagnostic tool for the detection of gastro-intestinal cancers is available.

Aged↗
PubMedDate not supplied

[Video-electroencephalography prolonged monitoring in patients with ambulatory diagnosis of medically refractory temporal lobe epilepsy: application of fuzzy logic's model].

INTRODUCTION: The video-electroencephalography (video-EEG) prolonged monitoring is an important auxiliary diagnostic instrument in epilepsy, and provides valuable information to classify the type of crisis and epileptic syndromes and to localize the epileptogenic zone. The fuzzy logic gives an efficient and intelligent analysis method, able to make inferences over ambiguous systems, and has been increasing used in several areas. AIMS: To correlate clinical and electroencephalographic data obtained with video-EEG of patients with clinical and interictal electroencephalography criteria of medically refractory temporal lobe epilepsy (TLE) and to make inferences of diagnosis precision with the application of the Fuzzy Hierarchy COPPE/Cosenza Model; to investigate the frequency in which the clinical, syndromic and topographic diagnosis can be modified in these patients; to evaluate the usefulness and applicability of fuzzy logic on the analysis of this type of study. PATIENTS AND METHODS: Transversal, prospective study, that included 22 adult outpatients with ambulatory diagnosis of medically refractory TLE, submitted to video-EEG monitoring that varied from 48 hours to 10 days. The grade of diagnosis precision was infered by fuzzy logic. RESULTS: The clinical diagnosis of epilepsy was modified in two (9%) patients, the syndromic in six (27.2%) and the topographic in 16 (72.7%). The fuzzy indicators of ambulatory diagnostic precision were: 0.91 to clinical diagnosis; 0.74 to syndromic diagnosis and 0.36 to topographic diagnosis, considering 1 the maximal precision diagnostic value (attributed to the video-EEG results). CONCLUSIONS: The video-EEG prolonged monitoring established the clinical, syndromic and topographic correct diagnosis in these patients; the fuzzy logic best defined a mathematical value of the correspondence between ambulatorial diagnosis of TLE and the video-EEG prolonged monitoring.

Adult↗