Block [Block, N. . Two neural correlates of consciousness. Trends in Cognitive Science, 9, 46–52] and Snodgrass claim that a signal detection theory analysis of qualitative difference paradigms, in particular the exclusion failure paradigm, reveals cases of phenomenal consciousness without access consciousness. This claim is unwarranted on several grounds. First, partial cognitive access rather than a total lack of cognitive access can account for exclusion failure results. Second, Snodgrass’s Objective Threshold/Strategic model of perception relies on a problematic ‘enable’ (...) approach to perception that denies the possibility of intentional control of unconscious perception and any effect of following different task instructions on the presence/absence of phenomenal consciousness. Many of Block’s purported examples of phenomenal consciousness without cognitive access also rely on this problematic approach. Third, qualitative difference paradigms may index only a subset of access consciousness. Thus, qualitative difference paradigms like exclusion failure cannot be used to isolate phenomenal consciousness, any attempt to do so still faces serious methodological problems. (shrink)

The Hilbert space formalism is a powerful language to express many cognitive phenomena. Here, relevant concepts from signal detection theory are recast in that language, allowing an empirically testable extension of the quantum probability formalism to psychophysical measures, such as detectability and discriminability.

Detection theory has been applied to a host of varied problems (for example, measuring the accuracy of diagnostic systems or reliability of lie detection tests) and extends far beyond the detection of signals. This book is a primer on the subject.

When we are fatigued, we feel that our performance is worse than when we are fresh. Yet, for over 100 years, researchers have been unable to identify an objective, behavioral measure that covaries with the subjective experience of fatigue. Previous work suggests that the metrics of signal detection theory —response bias and perceptual certainty —may change as a function of fatigue, but no work has yet been done to examine whether these metrics covary with fatigue. Here, we investigated (...) cognitive fatigue using SDT. We induced fatigue through repetitive performance of the n-back working memory task, while functional magnetic resonance imaging data was acquired. We also assessed cognitive fatigue at intervals throughout. This enabled us to assess not only whether criterion and d’ covary with cognitive fatigue but also whether similar patterns of brain activation underlie cognitive fatigue and SDT measures. Our results show that both criterion and d’ were correlated with changes in cognitive fatigue: as fatigue increased, subjects became more conservative in their response bias and their perceptual certainty declined. Furthermore, activation in the striatum of the basal ganglia was also related to cognitive fatigue, criterion, and d’. These results suggest that SDT measures represent an objective measure of cognitive fatigue. Additionally, the overlap and difference in the fMRI results between cognitive fatigue and SDT measures indicate that these measures are related while also separate. In sum, we show the relevance of SDT measures in the understanding of fatigue, thus providing researchers with a new set of tools with which to better understand the nature and consequences of cognitive fatigue. (shrink)

Collerton et al.'s Perception and Attention Deficit model argues that all recurrent complex visual hallucinations result from maladaptive, deficient sensory and attentional processing. We outline a constructivist-based representation of perception using signal detection theory, in which hallucinations are modeled as false alarms when confirmational perceptual information is lacking. This representation allows for some individuals to have RCVH due to a criterion shift associated with attentional proficiency that results in an increased awareness of the environment.

Phillips argues that blindsight is due to response criterion artefacts under degraded conscious vision. His view provides alternative explanations for some studies, but may not work well when one considers several key findings in conjunction. Empirically, not all criterion effects are decidedly non-perceptual. Awareness is not completely abolished for some stimuli, in some patients. But in other cases, it was clearly impaired relative to the corresponding visual sensitivity. This relative dissociation is what makes blindsight so important and interesting.

Signal detection theory (SDT) is best known as a method for separating sensitivity from bias. If sensitivity reflects early sensory processing and bias later cognition, then SDT can be use to study penetrability by asking whether cognitive manipulations affect sensitivity. This assumption is too simple, but SDT can nonetheless be helpful in developing specific methods of how sensory and cognitive information combine. Two such approaches are described.

Several conclusions depend on a version of signal detection theory that assumes performance is based on underlying equal-variance normal distributions of trace strength. Such conclusions are questionable without empirical justification for that assumption. A thought experiment is presented to show how the assumption is probably invalid, and empirical evidence is cited for the assumption's invalidity in research on human memory.

Introspection is a fundamental part of our mental lives. Nevertheless, its reliability and its underlying cognitive architecture have been widely disputed. Here, I propose a principled way to model introspection. By using time-tested principles from signal detection theory (SDT) and extrapolating them from perception to introspection, I offer a new framework for an introspective signal detection theory (iSDT). In SDT, the reliability of perceptual judgments is a function of the strength of an internal perceptual response (signal- (...) to-noise ratio) which is, to a large extent, driven by the intensity of the stimulus. In parallel to perception, iSDT models the reliability of introspective judgments as a function of the strength of an internal introspective response (signal-to-noise ratio) which is, to a large extent, driven by the intensity of conscious experiences. Thus, by modelling introspection after perception, iSDT can calibrate introspection’s reliability across a whole range of contexts. iSDT offers a novel, illuminating way of thinking about introspection and the cognitive processes that support it. (shrink)

Starting from macroscopic and microscopic facts of cerebellar histology, we propose a new functional interpretation that may elucidate the role of the cerebellum in movement control. The idea is that the cerebellum is a large collection of individual lines (Eccles's : Eccles et al. 1967a) that respond specifically to certain sequences of events in the input and in turn produce sequences of signals in the output. We believe that the sequence-in/sequence-out mode of operation is as typical for the cerebellar cortex (...) as the transformation of sets into sets of active neurons is typical for the cerebral cortex, and that both the histological differences between the two and their reciprocal functional interactions become understandable in the light of this dichotomy. The response of Purkinje cells to sequences of stimuli in the mossy fiber system was shown experimentally by Heck on surviving slices of rat and guinea pig cerebellum. Sequential activation of a row of eleven stimulating electrodes in the granular layer, imitating a of the stimuli along the folium, produces a powerful volley in the parallel fibers that strongly excites Purkinje cells, as evidenced by intracellular recording. The volley, or has maximal amplitude when the stimulus moves toward the recording site at the speed of conduction in parallel fibers, and much smaller amplitudes for lower or higher The succession of stimuli has no effect when they in the opposite direction. Synchronous activation of the stimulus electrodes also had hardly any effect. We believe that the sequences of mossy fiber activation that normally produce this effect in the intact cerebellum are a combination of motor planning relayed to the cerebellum by the cerebral cortex, and information about ongoing movement, reaching the cerebellum from the spinal cord. The output elicited by the specific sequence to which a is tuned may well be a succession of well timed inhibitory volleys the motor sequences so as to adapt them to the complicated requirements of the physics of a multijointed system. (shrink)

Nous voulons montrer que les théories générales de la dépiction et les théories de la photographie diffèrent dans la manière dont elles ont jusqu’à présent mobilisé la notion de ressemblance. En insistant sur la différence entre peinture et photographie, et sur la photographie en tant qu’ensemble de produits plutôt que sur la photographie en tant que technologie de production d’images, la plupart des théories existantes de la photographie se sont empêchées de comprendre quel est le rôle exact de la ressemblance (...) dans la dépiction photographique. Nous soulignons ce fait et suggérons qu’une distinction entre détection et dépiction est essentielle pour permettre le renouvellement de la philosophie de la photographie. (shrink)

ObjectivesBuilding on what is known about the non-random nature of crime problems and the explanatory capacity of opportunity theories of crime, this study explores the utility of using existing university administrative data to detect unusual patterns of performance consistent with a student having engaged in contract cheating (paying a third-party to produce unsupervised work on their behalf).MethodsResults from an Australian university were analysed (N = 3798 results, N = 1459 students). Performances on unsupervised and supervised assessment items were converted to (...) percentages and percentage point differences analysed at the academic discipline-, unit-, and student-level, looking for non-random patterns of unusually large differences.ResultsNon-random, unusual patterns, consistent with contract cheating, were found at the academic discipline-, unit-, and student-level, with approximately 2.1% of students producing multiple unusual patterns.ConclusionsThese findings suggest it may be possible to use existing administrative data to identify assessment items that provide suitable opportunities for contract cheating. This approach could be used in conjunction with targeted problem-prevention strategies (based on situational crime prevention) to reduce the vulnerability of academic assessment items to contract cheating. This approach is worthy of additional research as it has the potential to help academic institutions around the world manage contract cheating; a problem that currently threatens the validity and integrity of tertiary qualifications. (shrink)

Nous voulons montrer que les théories générales de la dépiction et les théories de la photographie diffèrent dans la manière dont elles ont jusqu’à présent mobilisé (ou non) la notion de ressemblance. En insistant sur la différence entre peinture et photographie, et sur la photographie en tant qu’ensemble de produits (les images photographiques) plutôt que sur la photographie en tant que technologie de production d’images, la plupart des théories existantes de la photographie se sont empêchées de comprendre quel est le (...) rôle exact de la ressemblance dans la dépiction photographique. Nous soulignons ce fait et suggérons qu’une distinction entre détection et dépiction est essentielle pour permettre le renouvellement de la philosophie de la photographie. (shrink)

The biological function of human reasoning abilities cannot be to improve shared knowledge. This is at best a side effect. A more plausible function of argumentation, and thus of reasoning, is to advertise one's ability to detect lies and errors. Such selfish behavior is closer to what we should expect from a naturally selected competence.

Two recently proposed experiments by Kolen and Torr (K-T), designed to detect possible failures of Einstein's special relativity (SR) are analyzed. Imprecisions in these papers are pointed out. Computation in Lorentz aether theory (LAT), with the K-T violation of SR, of the theoretical prediction for the proposed K-T clock experiment prove their results to be incorrect. Analytical computation of the proposed K-T rotor Doppler experiment using LAT confirms the order of magnitude of their prediction by numerical computation. For LAT (...) in the K-T form, this experiment, using a turntable, is shown to give results which could be detected with the technology of 20 years ago. Another LAT model is considered which leads to deviations of SR smaller than in the K-T model. The central point of the approach adopted in this paper is the use of Einstein's coordinates in the comoving frame, even when SR is violated, leading always to isotropic propagation of light in vacuum; the anisotropy usually obtained in LAT is only a coordinate effect. (shrink)

Chris N. H. Street Behavioral and Social Sciences Department, University of Huddersfield, UK We are very inaccurate lie detectors, and … Read More →.