Sylvan Kornblum

Dimensional Overlap: Cognitive Basis for Stimulus-Response Compatibility— A Model and Taxonomy

The classic problem of stimulus-response (S-R) compatibility (SRC) is addressed. A cognitive model is proposed that views the stimulus and response sets in S-R ensembles as categories with dimensions that may or may not overlap. If they do overlap, the task may be compatible or incompatible, depending on the assigned S-R mapping. If they do not overlap, the task is noncompatible regardless of the assigned mapping. The overlapping dimensions may be relevant or not. The model provides a systematic account of SRC effects, a taxonomy of simple performance tasks that were hitherto thought to be unrelated, and suggestive parallels between these tasks and the experimental paradigms that have traditionally been used to study attentional, controlled, and automatic processes.

Eye-hand coordination: oculomotor control in rapid aimed limb movements

Three experiments are reported in which Ss produced rapid wrist rotations to a target while the position of their eyes was being monitored. In Experiment 1, Ss spontaneously executed a saccadic eye movement to the target around the same time as the wrist began to move. Experiment 2 revealed that wrist-rotation accuracy suffered if Ss were not allowed to move their eyes to the target, even when visual feedback about the moving wrist was unavailable. In Experiment 3, wrist rotations were equally accurate when Ss produced either a saccadic or a smooth-pursuit eye movement to the target. However, differences were observed in the initial-impulse and error-correction phases of the wrist rotations, depending on the type of eye movement involved. The results suggest that aimed limb movements use information from the oculomotor system about both the static position of the eyes and the dynamic characteristics of eye movements. Furthermore, the information that governs the initial impulse is different from that which guides final error corrections.

The way irrelevant dimensions are processed depends on what they overlap with: The case of Stroop- and Simon-like stimuli

SummaryAccording to the dimensional-overlap model (Kornblum, 1992), irrelevant dimensions that overlap with a stimulus dimension (e. g., Stroop-type stimuli) are processed by a different stage than those that overlap with the response (e. g., Simon-type stimuli). We show that the effects of these two types of overlap are additive, thus supporting the models hypothesis. We also show that the time course of facilitation and interference is different for these two types of overlap.

A PRIMING METHOD FOR INVESTIGATING THE SELECTION OF MOTOR RESPONSES

Abstract We describe a priming method for investigating the mechanisms underlying the selection of motor responses. The empirical question addressed with the method is how the choice reaction time for a response depends on its relationship to a response that the subject was primed to perform. We explore the method in a study of manual response selection where we investigate the effects of requiring that two possible responses use the same finger or hand. A requirement of the method — that subjects get ready to perform primed responses only — is not met in some conditions of the experiment. When the two possible responses are made with different hands, it appears that multiple response preparation occurs prior to detection of the reaction signal, whereas when the two possible responses are made with different fingers of the same hand it appears that advance preparation is limited to a single response. This finding implies that subjects engage in different kinds of response preparation depending on the relationship between the alternative possible responses. We discuss the implications of this hypothesis for the priming method introduced here as well as for theories of response selection generally.

A Parallel Distributed Processing Model of Stimulus-Stimulus and Stimulus-Response Compatibility.

A parallel distributed processing (PDP) model is proposed to account for choice reaction time (RT) performance in diverse cognitive and perceptual tasks such as the Stroop task, the Simon task, the Eriksen flanker task, and the stimulus-response compatibility task that are interrelated in terms of stimulus-stimulus and stimulus-response overlap (Kornblum, 1992). In multilayered (input-intermediate-output) networks, neuron-like nodes that represent stimulus and response features are grouped into mutually inhibitory modules that represent stimulus and response dimensions. The stimulus-stimulus overlap is implemented by a convergence of two input modules onto a common intermediate module, and the stimulus-response overlap by direct pathways representing automatic priming of outputs. Mean RTs are simulated in various simple tasks and, furthermore, predictions are generated for complex tasks based on performance in simpler tasks. The match between simulated and experimental results lends strong support for our PDP model of compatibility.

CHANGES IN MEDIAL CORTICAL BLOOD FLOW WITH A STIMULUS-RESPONSE COMPATIBILITY TASK

Previous work has suggested that human subjects engaged in tasks, like the Stroop task, that require response selection utilize the medial frontal cortex. We used positron emission tomography to measure blood flow changes in a stimulus-response compatibility task designed to maximize the demand on response selection processes. We report significant activation in the cingulate sulcus (Brodmans area 32) and a correlation of activity in this region with faster response time for an incongruent stimulus-response task.

Response competition and/or inhibition in two-choice reaction time

A two-choice reaction time experiment was conducted in which it was demonstrated that the reaction time for a particular finger is subject to change depending on the alternatives with which it is paired. This finding, it is argued, raises questions regarding the adequacy of controls which select the experimental data from only one finger in an effort to minimize the effects of inter-finger variability. It is also a dem onstration of R-R compatibility effects, and as such, lends experimental support to the hypothesis that a measurable portion of the reaction time interval is consumed by the processes associated with the inhibition of competing incorrect response alternatives.

Distributional Analysis and De Jong, Liang, and Lauber's (1994) Dual-Process Model of the Simon Effect

Marsh, 1975), respectively. It is also shown that the distributional analysis is a simple computational procedure that reflects fundamental statistical properties of the underlying reaction time distributions and their interrelationships and that De Jong et al.s time-course assumptions precluded at least half of these interrelationships. Indeed, experimental results from tasks in which the Simon effect is obtained often violate these assumptions, as is demonstrated in this article. Finally, it is also shown that De Jong et al.s data are consistent with the hypothesis that the Simon effect and its reversal, irrespective of the task type in which it is obtained, can be accounted for by a common mechanism with 2 independent functional components.

The Effects of Stimulus-Response Mapping and Irrelevant Stimulus-Response and Stimulus-Stimulus Overlap in Four-Choice Stroop Tasks With Single-Carrier Stimuli

The purpose of this study was to investigate whether and how stimulus-stimulus (SS) and stimulus-response (SR) consistency and SR congruence effects combine to produce the Stroop effect. Two experiments were conducted with 4-choice tasks in which SS and SR consistency and SR congruence effects were examined in isolation as well as in the Stroop task. The experiments were so designed as to remove the confound between SS and SR consistency that is ordinarily found in standard Stroop tasks and to pit SS consistency against the logical recording hypothesis (A. Hedge & N. W. A. Marsh, 1975). The results indicate that SS and SR consistency both contribute to the Stroop effect and that they interact. This finding supports models such as the dimensional overlap model (e.g., S. Kornblum & J. W. Lee, 1995) that distinguish between SS and SR overlap. Simulation results from an interactive activation network, modeled after the dimensional overlap model, provide reasonable fits to the experimental data.

Neuronal correlates of sensorimotor association in stimulus-response compatibility.

Neuronal mechanisms underlying stimulus-response (S-R) associations in S-R compatibility tasks were identified in 2 experiments with monkeys. Visual stimuli were presented on the left and right calling for left-right movements under congruent and incongruent S-R mapping instructions. High- and low-pitched tones calling for left-right movements were presented to the left and right ear, and the stimulus side was irrelevant. Single neurons sensitive to the S-R mapping rule were found in the primary motor cortex. The large overlap between the neuronal populations sensitive to the stimulus side, the S-R mapping rule, and the response side, respectively, is consistent with the idea that sensory-to-motor transformation is a continuous rather than a discrete process. Results partly support the hypothesis that the increase in reaction time with incongruent mapping is caused by the automatic activation of the congruent, but erroneous, response.