Visual-auditory interaction in speeded classification: Role of stimulus difference

An experiment examined cross-modal interference and congruence in speeded classification: Subjects had to identify compound (visual-auditory) stimuli as either low or high in spatial position (visual judgment) or low or high in pitch (auditory judgment), in 16 conditions, each of which combined one of four possible pairs of tones, varying in frequency difference, with one of four possible pairs of dots, varying in positional difference. Both classification by position and classification by pitch revealed Garner interference (poorer performance than baseline, with orthogonal variation in the irrelevant dimension) and congruence effects (better performance with congruent than with incongruent stimulus combinations), but pitch classification showed more. Furthermore, the size of the pitch difference strongly affected classification by pitch and less strongly affected classification by position, but the size of the position difference affected neither. The findings are consistent with the view that Garner interference and congruence effects are closely related, perhaps arising from a common source, and suggest that the asymmetries could depend in part on the degree of dimensional overlap between stimuli and responses.     

An exemplar-retrieval model of speeded same--different judgments

R. M. Nosofsky and T. J. Palmeri's (1997) exemplar-based random-walk (EBRW) model of speeded classification is extended to account for speeded same--different judgments among integral-dimension stimuli. According to the model, an important component process of same--different judgments is that people store individual examples of experienced same and different pairs of objects in memory. These exemplar pairs are retrieved from memory on the basis of how similar they are to a currently presented pair of objects. The retrieved pairs drive a random-walk process for making same--different decisions. The EBRW predicts correctly that same responses are faster for objects lying in isolated than in dense regions of similarity space. The model also predicts correctly effects of same-identity versus same-category instructions and is sensitive to observers' past experiences with specific same and different pairs of objects.     

Modelling cognition in emotional disorder: The S-REF model

Cognitive therapy techniques are applied to an ever-increasing range of psychological disorders. However, both basic methods and general theory of therapy have evolved more slowly. Although cognitive therapy is based on experimentally testable concepts derived from cognitive psychology, an integration of these areas capable of explaining cognitive-attentional phenomena and offering treatment Implications remains to be achieved. In this paper, we outline the Self-Regulatory Executive Function (S-REF) model of emotional disorder, which integrates information processing research with Beck's schema theory. The model advances understanding of the roles of stimulus-driven and voluntary control of cognition, procedural knowledge (beliefs), and of the interactions between different levels of information-processing. It also accounts for cognitive bias effects demonstrated in the experimental psychopathology literature. The model presents implications concerning not only what should be done in cognitive therapy, but how cognitive change may be most effectively accomplished.     

A crossed random effects diffusion model for speeded semantic categorization decisions

Choice reaction times (RTs) are often used as a proxy measure of typicality in semantic categorization studies. However, other item properties have been linked to choice RTs as well. We apply a tailored process model of choice RT to a speeded semantic categorization task in order to deconfound different sources of variability in RT. Our model is based on a diffusion model of choice RT, extended to include crossed random effects (of items and participants). This model retains the interesting process interpretation of the diffusion model’s parameters, but it can be applied to choice RTs even in the case where there are few or no repeated measurements of each participant-item combination. Different aspects of the response process are then linked to different types of item properties. A typicality measure turns out to predict the rate of information uptake, while a lexicographic measure predicts the stimulus encoding time. Accessibility measures cannot reliably predict any component of the decision process.     

A constructivist model of infant cognition

We propose six Information-Processing Principles (IPPs) that together describe a constructive, hierarchical system by which infants come to understand objects and events in the world around them. We then demonstrate the applicability of these principles to four specific domains of infant perception and/or cognition, (i.e., form perception, object unity, complex pattern perception, and understanding of causal events). In each case empirical developmental changes appear to be consistent with the IPPs. We then present the Constructivist Learning Architecture, a computational model of infant cognitive development. This model is based on the IPPs, and uses self-organizing, neurally based techniques from Kohonen (1997) and Hebb (1949). We then apply the model to the complex domain of infant understanding of causal events, and replicate many of the developmental changes found empirically. Finally, we discuss the applicability of this constructivist approach to infant cognitive development in general.     

The reliability of speeded tests

Some methods are presented for estimating the reliability of a partially speeded test without the use of a parallel form. The effect of these formulas on some test data is illustrated. Whenever an odd-even reliability is computed it is probably desirable to use one of the formulas noted in Section 2 of this paper in addition to the usual Spearman-Brown correction. Since the formulas given here involve the mean and the standard deviation of the “number unattempted score,” a method is given in Section 4 for computing this mean and standard deviation from item analysis data. If the item analysis data are available, this method will save considerable time as compared with rescoring answer sheets.     

The tuning-fork model of human social cognition: a critique

The tuning-fork model of human social cognition, based on the discovery of mirror neurons (MNs) in the ventral premotor cortex of monkeys, involves the four following assumptions: (1) mirroring processes are processes of resonance or simulation. (2) They can be motor or non-motor. (3) Processes of motor mirroring (or action-mirroring), exemplified by the activity of MNs, constitute instances of third-person mindreading, whereby an observer represents the agent's intention. (4) Non-motor mirroring processes enable humans to represent others' emotions. After questioning all four assumptions, I point out that MNs in an observer's brain could not synchronically resonate with MNs in an agent's brain unless they discharged in a single brain in two distinct tasks at different times. Finally, I sketch a conceptualist alternative to the resonance model according to which a brain mechanism active in both the execution and the perception of e.g., the act of grasping is the neural basis of the concept of e.g., grasping.     

The dynamics of cognition: An ACT-R model of cognitive arithmetic

Zusammenfassung. Forschungsarbeiten zur Kognitiven Arithmetik untersuchen die mentale Repräsentation von Zahlen und arithmetischen Fakten sowie die kognitiven Prozesse die diese generieren, abrufen und manipulieren. Das Spannungsfeld zwischen der scheinbar einfachen formalen Struktur dieses Aufgabenbereichs und den Schwierigkeiten, die Kinder bei seiner Bewältigung haben, stellt einen einzigartigen Zugang zum Studium kognitiver Prozesse dar. Der vorliegende Beitrag präsentiert einen Erklärungsansatz der zentralen Befunde des Forschungsgebietes auf der Grundlage eines ACT-R Modells zur Lebenszeit-Simulation des Erwerbs arithmetischen Wissens. Die Anwendung der Bayesischen Lernmechanismen der ACT-R Architektur zeigen auf, wie sich diese Befunde auf die statistische Struktur des Aufgabengebiets zurückführen lassen. Aus den präzisen Vorhersagen der Simulation werden sowohl Hinweise zur Vermittlung arithmetischen Wissens abgeleitet als auch Erkenntnisse über die Architektur ACT-R selbst gewonnen. Im Rahmen einer formalen Analyse wird gezeigt, daß sich die vorgestellte Simulation als dynamisches System betrachten läßt, dessen Lernergebnis unmittelbar von Parametern der Architektur abhängt. Eine Untersuchung der Sensitivität der Parameter der Simulation belegt, daß die Werte, die zur besten Anpassung an die empirischen Daten führen, auch eine in einer optimalen Performanz resultieren. Die Implikationen dieses Ergebnis für die grundlegende Adaptivität menschlicher Kognition werden diskutiert. Abstract. Cognitive arithmetic studies the mental representation of numbers and arithmetic facts and the processes that create, access, and manipulate them. The contradiction between the apparent straightforwardness of its exact formal structure and the difficulties that every child faces in mastering it provides an important window into human cognition. An ACT-R model is proposed which accounts for the central results of the field through a single simulation of a lifetime of arithmetic learning. The use of the architecture's Bayesian learning mechanisms explains how these effects arise from the statistics of the task. Because of the precise predictions of the simulation, a number of lessons are derived concerning the teaching of arithmetic and the ACT-R architecture itself. A formal analysis establishes that the simulation can be viewed as a dynamical system whose ultimate learning outcome is fundamentally dependent upon some architectural parameters. Finally, an empirical study of the sensitivity of the simulation to its parameters determines that the values that yield the best fit to the data also provide optimal performance. The implications of these findings for the fundamental adaptivity of human cognition are discussed.     

A computational model of anterior cingulate function in speeded response tasks: effects of frequency,sequence, and conflict

A growing body of evidence from functional neuroimaging and computational modeling studies indicates that the anterior cingulate cortex (ACC) detects the presence of response conflict and conveys this information to other brain regions, enabling subsequent adjustments in cognitive control. The present study examined previous empirical findings of increased ACC for low-frequency stimuli across three distinct speeded response tasks (two-alternative forced choice, go/no-go, and oddball). Simulations conducted in a neural network model incorporating sequential priming mechanisms (developed in Cho et al., 2002) confirmed that a computational measure of response conflict was higher on low-frequency trials across all three tasks. In addition, the model captured detailed aspects of behavioral reaction time and accuracy data, predicted the dynamics of ACC activity related to trial sequence effects, and provided evidence for the functional role of conflict information in performance monitoring and optimization. The results indicate that the conflict-monitoring hypothesis, augmented by mechanisms for encoding stimulus history, can explain key phenomena associated with performance in sequential speeded response tasks.     

The role of background knowledge in speeded perceptual categorization

We examined the time-course of the influence of background knowledge on perceptual categorization by manipulating the meaningfulness of labels associated with categories and by manipulating the amount of time provided to subjects for making a categorization decision. Extending a paradigm originally reported by Wisniewski and Medin (1994) (Cog. Sci. 18 (1994) 221), subjects learned two categories of children's drawings that were given either meaningless labels (drawings by children from 'group 1' or 'group 2') or meaningful labels (drawings by 'creative' or 'non-creative' children); the meaningfulness of the label had a significant effect on how new drawings were classified. In addition, half of the subjects were provided unlimited time to respond, while the other half of the subjects were forced to respond quickly; speeded response conditions had a relatively large effect on categorization decisions by subjects given the meaningless labels but had relatively little effect on categorization decisions by subjects given the meaningful labels. These results suggest that some forms of background knowledge can show an influence at relatively early stages in the time-course of a categorization decision.     

On cross-modal similarity: auditory-visual interactions in speeded discrimination

A series of four experiments explored how cross-modal similarities between sensory attributes in vision and hearing reveal themselves in speeded, two-stimulus discrimination. When subjects responded differentially to stimuli on one modality, speed and accuracy of response were greater on trials accompanied by informationally irrelevant "matching" versus "mismatching" stimuli from the other modality. Cross-modal interactions appeared in (a) responses to dim/bright lights and to dark/light colors accompanied by low-pitched/high-pitched tones; (b) responses to low-pitched/high-pitched tones accompanied by dim/bright lights or by dark/light colors; (c) responses to dim/bright lights, but not to dark/light colors, accompanied by soft/loud sounds; and (d) responses to rounded/sharp forms accompanied by low-pitched/high-pitched tones. These results concur with findings on cross-modal perception, synesthesia, and synesthetic metaphor, which reveal similarities between pitch and brightness, pitch and lightness, loudness and brightness, and pitch and form. The cross-modal interactions in response speed and accuracy may take place at a sensory/perceptual level of processing or after sensory stimuli are encoded semantically.     

A mechanism for error detection in speeded response time tasks

The concept of error detection plays a central role in theories of executive control. In this article, the authors present a mechanism that can rapidly detect errors in speeded response time tasks. This error monitor assigns values to the output of cognitive processes involved in stimulus categorization and response generation and detects errors by identifying states of the system associated with negative value. The mechanism is formalized in a computational model based on a recent theoretical framework for understanding error processing in humans (C. B. Holroyd & M. G. H. Coles, 2002). The model is used to simulate behavioral and event-related brain potential data in a speeded response time task, and the results of the simulation are compared with empirical data.     

Polarity correspondence: A general principle for performance of speeded binary classification tasks

Differences in performance with various stimulus-response mappings are among the most prevalent findings for binary choice reaction tasks. The authors show that perceptual or conceptual similarity is not necessary to obtain mapping effects; a type of structural similarity is sufficient. Specifically, stimulus and response alternatives are coded as positive and negative polarity along several dimensions, and polarity correspondence is sufficient to produce mapping effects. The authors make the case for this polarity correspondence principle using the literature on word-picture verification and then provide evidence that polarity correspondence is a determinant of mapping effects in orthogonal stimulus-response compatibility, numerical judgment, and implicit association tasks. The authors conclude by discussing implications of this principle for interpretation of results from binary choice tasks and future model development.     

The influence of irrelevant information on speeded classification tasks

Multidimensional stimuli, which could vary on one, two, or all three dimensions within a particular series, were presented to Ss who were required to classify each stimulus on the basis of its value on a specified dimension. The prior relevance of the irrelevant dimensions and the difficulty of the task were varied. Latency and error data indicated that Ss were unable to gate the irrelevant information effectively. It was further concluded that this lack of perfect gating cannot be simply attributed to competing responses learned during the experiment.