Adele Diederich

Bimodal and trimodal multisensory enhancement: Effects of stimulus onset and intensity on reaction time

Manual reaction times to visual, auditory, and tactile stimuli presented simultaneously, or with a delay, were measured to test for multisensory interaction effects in a simple detection task with redundant signals. Responses to trimodal stimulus combinations were faster than those to bimodal combinations, which in turn were faster than reactions to unimodal stimuli. Response enhancement increased with decreasing auditory and tactile stimulus intensity and was a U-shaped function of stimulus onset asynchrony. Distribution inequality tests indicated that the multisensory interaction effects were larger than predicted by separate activation models, including the difference between bimodal and trimodal response facilitation. The results are discussed with respect to previous findings in a focused attention task and are compared with multisensory integration rules observed in bimodal and trimodal superior colliculus neurons in the cat and monkey.

Survey of decision field theory

Abstract This article summarizes the cumulative progress of a cognitive-dynamical approach to decision making and preferential choice called decision field theory. This review includes applications to (a) binary decisions among risky and uncertain actions, (b) multi-attribute preferential choice, (c) multi-alternative preferential choice, and (d) certainty equivalents such as prices. The theory provides natural explanations for violations of choice principles including strong stochastic transitivity, independence of irrelevant alternatives, and regularity. The theory also accounts for the relation between choice and decision time, preference reversals between choice and certainty equivalents, and preference reversals under time pressure. Comparisons with other dynamic models of decision-making and other random utility models of preference are discussed.

Multisensory Interaction in Saccadic Reaction Time: A Time-Window-of-Integration Model

Saccadic reaction time to visual targets tends to be faster when stimuli from another modality (in particular, audition and touch) are presented in close temporal or spatial proximity even when subjects are instructed to ignore the accessory input (focused attention task). Multisensory interaction effects measured in neural structures involved in saccade generation (in particular, the superior colliculus) have demonstrated a similar spatio-temporal dependence. Neural network models of multisensory spatial integration have been shown to generate convergence of the visual, auditory, and tactile reference frames and the sensorimotor coordinate transformations necessary for coordinated head and eye movements. However, because these models do not capture the temporal coincidences critical for multisensory integration to occur, they cannot easily predict multisensory effects observed in behavioral data such as saccadic reaction times. This article proposes a quantitative stochastic framework, the time-window-of-integration model, to account for the temporal rules of multisensory integration. Saccadic responses collected from a visualtactile focused attention task are shown to be consistent with the time-window-of-integration model predictions.

Evaluating and Combining Subjective Probability Estimates

This paper concerns the evaluation and combination of subjective probability estimates for categorical events. We argue that the appropriate criterion for evaluating individual and combined estimates depends on the type of uncertainty the decision maker seeks to represent, which in turn depends on his or her model of the event space. Decision makers require accurate estimates in the presence of aleatory uncertainty about exchangeable events, diagnostic estimates given epistemic uncertainty about unique events, and some combination of the two when the events are not necessarily unique, but the best equivalence class definition for exchangeable events is not apparent. Following a brief reveiw of the mathematical and empirical literature on combining judgments, we present an approach to the topic that derives from (1) a weak cognitive model of the individual that assumes subjective estimates are a function of underlying judgment perturbed by random error and (2) a classification of judgment contexts in terms of the underlying information structure. In support of our developments, we present new analyses of two sets of subjective probability estimates, one of exchangeable and the other of unique events. As predicted, mean estimates were more accurate than the individual values in the first case and more diagnostic in the second. #1997 by John Wiley & Sons, Ltd.

Simple matrix methods for analyzing diffusion models of choice probability, choice response time, and simple response time

Abstract Diffusion processes (e.g., Wiener process, Ornstein–Uhlenbeck process) are powerful approaches to model human information processes in a variety of psychological tasks. Lack of mathematical tractability, however, has prevented broad applications of these models to empirical data. This tutorial explains step by step, using a matrix approach, how to construct these models, how to implement them on a computer, and how to calculate the predictions made by these models. In particular, we present models for binaries choices for unidimensional and multiattribute choice alternatives; for simple reaction time tasks; and for three alternatives choice problems.

Assessing age-related multisensory enhancement with the time-window-of-integration model

Although from multisensory research a great deal is known about how the different senses interact, there is little knowledge as to the impact of aging on these multisensory processes. In this study, we measured saccadic reaction time (SRT) of aged and young individuals to the onset of a visual target stimulus with and without an accessory auditory stimulus occurring (focused attention task). The response time pattern for both groups was similar: mean SRT to bimodal stimuli was generally shorter than to unimodal stimuli, and mean bimodal SRT was shorter when the auditory accessory was presented ipsilaterally rather than contralaterally to the target. The elderly participants were considerably slower than the younger participants under all conditions but showed a greater multisensory enhancement, that is, they seem to benefit more from bimodal stimulus presentation. In an attempt to weigh the contributions of peripheral sensory processes relative to more central cognitive processes possibly responsible for the difference in the younger and older adults, the time-window-of-integration (TWIN) model for crossmodal interaction in saccadic eye movements developed by the authors was fitted to the data from both groups. The model parameters suggest that (i) there is a slowing of the peripheral sensory processing in the elderly, (ii) as a result of this slowing, the probability of integration is smaller in the elderly even with a wider time-window-of-integration, and (iii) multisensory integration, if it occurs, manifests itself in larger neural enhancement in the elderly; however, because of (ii), on average the integration effect is not large enough to compensate for the peripheral slowing in the elderly.

The Race Model Inequality: Interpreting a Geometric Measure of the Amount of Violation

An inequality by J. O. Miller (1982) has become the standard tool to test the race model for redundant signals reaction times (RTs), as an alternative to a neural summation mechanism. It stipulates that the RT distribution function to redundant stimuli is never larger than the sum of the distribution functions for 2 single stimuli. When many different experimental conditions are to be compared, a numerical index of violation is very desirable. Widespread practice is to take a certain area with contours defined by the distribution functions for single and redundant stimuli. Here this area is shown to equal the difference between 2 mean RT values. This result provides an intuitive interpretation of the index and makes it amenable to simple statistical testing. An extension of this approach to 3 redundant signals is presented.

Modeling the Effects of Payoff on Response Bias in a Perceptual Discrimination Task: Bound-Change, Drift-Rate-Change, or Two-Stage-Processing Hypothesis

Three hypotheses—thebound-change hypothesis, drift-rate-change hypothesis, andtwo-stageprocessing hypothesis—are proposed to account for data from a perceptual discrimination task in which three different response deadlines were involved and three different payoffs were presented prior to each individual trial. The aim of the present research was to show (1) how the three different hypotheses incorporate response biases into a sequential sampling decision process, (2) how payoffs and deadlines affect choice probabilities, and (3) the hypotheses’ predictions of response times and choice probabilities. The two-stage-processing hypothesis gave the best account, especially for the choice probabilities, whereas the drift-rate-change hypothesis had problems predicting choice probabilities as a function of deadlines. nt]mis|This research was supported by Deutsche Forschungsgemeinschaft Grant Di 506/6-2 to the first author.

Intersensory facilitation in the motor component

SummaryIn the bimodal detection task the observer must respond as soon as a signal is presented in either of two modalities (e.g., a tone or a flash). A typical finding is a facilitation of reaction time for redundant signal trials, that is, when both signals are presented simultaneously or with a short delay. Models advanced for this effect imply either statistical facilitation (separate activation) or intersensory facilitation (coactivation). This paper reports a study investigating whether part of the facilitation can be accounted for by coactivation in the motor component. An analysis of the distributions of reaction time differences between left and right hand responses from a double response paradigm gave some evidence in favor of this hypothesis. In particular, our data suggest a u-shaped functional dependence of the amount of facilitation in the motor component on the interstimulus interval.

Context Dependence and Aggregation in Disaggregate Choice Analysis

There is an emerging consensus among disciplines dealing with human decision making that the context in which a decision is made is an important determinant of outcomes. This consensus has been slow in the making because much of what is known about context effects has evolved from a desire to demonstrate the untenability of certain common assumptions upon which tractable models of behavior have generally been built. This paper seeks to␣bring disparate disciplinary perspectives to bear on the relation between context and choice, to formulate (1) recommendations for improvements to the state-of-the-practice of Random Utility Models (RUMs) of choice behavior, and (2) a future research agenda to guide the further incorporation of context into these models of choice behavior.