PubMed Health⌕ Search

Biomedical subjects

S Kornblum

Publications and source records attributed to S Kornblum.

At least 19 recordsLinked to original sources
PubMed1999

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.

Computer Simulation↗
PubMed1999

Stimulus-response compatibility effects in go-no-go tasks: a dimensional overlap account.

According to the automatic response activation hypothesis of the dimensional overlap (DO) model (Kornblum, Stevens, Whipple, & Requin, 1999), stimulus-response compatibility effects are expected to occur in go-no-go tasks. This prediction is confirmed in two experiments in which subjects moved a hand to one side of the field on presentation of a go stimulus. Although the direction of movement was known in advance and the spatial attribute of the go stimuli was irrelevant to the go-no-go decision, the subjects' response time was shorter when the spatial attribute to the go stimulus corresponded to that of the response than when it did not. These effects are shown to depend on the similarity of the go and the no-go stimuli, as well as on whether the spatial attribute of the go stimuli was its actual location or its meaning. We discuss these results in terms of the temporal dynamics of automatic and controlled response processes, as hypothesized in the DO model.

Adult↗
PubMed1998

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.

Conditioning, Psychological↗
PubMed1997

Dynamics of single neuron activity in monkey primary motor cortex related to sensorimotor transformation.

We investigated the dynamics of neuronal activity related to sensorimotor transformation during single experimental trials of a given stimulus-response (S-R) association task. A monkey was trained to perform wrist extension/flexion movements in the horizontal plane to align a pointer with a visual target while single unit activity in the primary motor cortex (MI) was being recorded. The stimulus was a colored light-emitting diode (LED) presented to either the left or right of a central reference point. The monkey had to point directly at the target ("compatible" S-R mapping) or point to the opposite side of the target position ("incompatible" S-R mapping), with the mapping rule specified by the color of the LED. Single neuron activities on the four correct trials (left/right stimulus x compatible/incompatible S-R mapping) were compared to determine whether such activities were more related to stimulus encoding and representation, to response preparation and execution, or to the "decision" processes translating the stimulus representation into a response representation. A novel mathematical technique, called LOCUS ANALYSIS, has been developed to quantitatively analyze and visualize the contribution of neuronal activity toward the sensory, motor, or sensorimotor (i.e., decisional) aspects of the task. Our data show that as a trial evolves, neuronal activity in MI, at a population level, is first correlated with the representation of the specific stimulus (the side of LED), then with the representation of the S-R mapping rule (the color of LED) as well as trial-specific S-R association (the conjunction of stimulus side and stimulus color), and finally with the representation of the behavioral response (extension or flexion wrist movement). Immediately after the issuance of the movement command, the populational activity in MI remains correlated with the trial-specific stimulus-response conjunctions, i.e., the context of the motor decision that the monkey has just made. Cells recorded successively in a single penetration tend to resemble each other in their pattern of firing on the four correct trials, suggesting a modular organization of neurons based on their functional role in the processing of the S-R association task. Our results indicate that MI belongs to a distributed network such that its neuronal activity reflects the underlying network dynamics that translate a stimulus representation into a response representation via the activation and application of appropriate S-R mapping rule.

Animals↗
PubMed1997

Isolation of specific interference processing in the Stroop task: PET activation studies.

The Stroop task, in which subjects must name the color of letters that spell color words different than the color-to-be-named, provides an important experimental paradigm for the study of selective attention. Cerebral blood flow activation studies have not always demonstrated consistent activation patterns; inconsistent results may reflect nonspecific responses, such as arousal or anticipation, rather than cerebral networks specific to Stroop interference processing. In order to identify regions consistently implicated in Stroop interference processing, we undertook two experiments with a Stroop interference paradigm and contrasting lexical and nonlexical control conditions. In our first experiment, standard Stroop stimuli, e.g., the word "RED" displayed in a green font, were contrasted with color naming of the font of noncolor words and color naming of a false font. In our second experiment, we compared Stroop stimuli with colored symbols and a control condition designed to elicit nonspecific interference-taboo words displayed in color fonts. Only two brain regions showed a consistent CBF change in both experiments. Activation in the left inferior frontal gyrus reflected processing more specific to the Stroop task, while deactivation in the right superior temporal gyrus occurred for the Stroop and the taboo conditions, consistent with more nonspecific processing. Activation in the anterior cingulate cortex occurred in only one comparison in one experiment and may not reflect functions central to overcoming Stroop interference.

Adult↗
PubMed1997

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.

Analysis of Variance↗
PubMed1995

Stimulus-response compatibility with relevant and irrelevant stimulus dimensions that do and do not overlap with the response.

Five experiments were conducted using 4- and 6-choice stimulus-response compatibility tasks with graphic and alphabetic stimuli, and keypress and verbal responses. A comparison of performance with compatible, incompatible, and neutral conditions shows that when a stimulus set is perceptually, conceptually, or structurally similar to a response set, (a) mean reaction times (RTs) are faster when individual stimuli and responses match than when they do not match, (b) this is true whether the stimulus and response sets are similar on relevant or irrelevant dimensions, (c) this "compatibility effect" is greater when the dimensions are relevant than when they are irrelevant, and (d) whether the dimensions are relevant or irrelevant, the faster RTs are due to a facilitative process and the slower RTs to an interfering process. These results are accounted for by the dimensional overlap model.

Cognition↗
PubMed1994

Neuronal coding of stimulus-response association rules in the motor cortex.

Two monkeys were trained to perform wrist movements to align a pointer with visual targets. In the spatially 'compatible' condition, monkeys had to point at the target position (left/right), whereas in the 'incompatible' condition, they had to point at the position opposite to the target. A large proportion of neurones recorded in the primary motor cortex showed changes in activity according to either the side of the target or the side of the movement. However, more than 40% of neurones changed their activity as a function of the stimulus-response mapping rule. Some of these neurones, being sensitive only to the stimulus-response compatibility effect, must therefore be viewed as specifically involved in the neural mechanisms that control the association process between sensory inputs and motor outputs.

Animals↗
PubMed1994

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

According 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 model's hypothesis. We also show that the time course of facilitation and interference is different for these two types of overlap.

Adult↗
PubMed1994

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 (Brodman's area 32) and a correlation of activity in this region with faster response time for an incongruent stimulus-response task.

Brain↗
PubMed1990

Does motor programming necessitate response execution?

The complexity of a movement is known to affect the time it takes to initiate the movement. This effect is thought to reflect changes in the duration of processes that operate on a motor program. This question addressed here is whether programming a movement compels the start of its overt execution. If it does, then the programming processes may be said to occur after the "point of no return." We report results from an empirical procedure and a theoretical analysis designed to study processes before and after this point separately. According to our results, changes in the complexity of a movement affect only the prior set of processes. From this we argue that motor programming does not necessitate response execution and that the point of no return occurs very late in the information-processing system.

Adult↗
PubMed1990

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.

Adult↗
PubMed1990

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.

Arousal↗
PubMed1989

Speed and accuracy of saccadic eye movements: characteristics of impulse variability in the oculomotor system.

Dynamic characteristics observed in the trajectories of saccadic eye movements reveal systematic variability of the force pulses used to move the eyes. This variability causes saccades to exhibit a linear speed-accuracy trade-off: As the average distance and duration of saccades toward specified target points increase, the standard deviations of saccadic-movement endpoints increase linearly with the saccades' average velocity. The linear trade-off, and other observed stochastic properties of saccades, may be attributed to noise in neuromotor processes and may be described in terms of an impulse-variability model originally designed for characterizing limb movements. According to the model, both eye and limb movements are controlled through stochastic force and time parameters that govern movement kinematics. Such an account may promote a unified conceptual framework for understanding a wide range of motor behavior.

Acceleration↗
PubMed1986

The point of no return in choice reaction time: controlled and ballistic stages of response preparation.

A countermanding procedure and race model are used to assess separately the effects of experimental factors before and after the "point of no return" in response preparation. The results reveal details about processes that so closely precede the initiation of movement that they cannot be inhibited. These processes appear to be affected by the repetition of stimulus-response pairs, but not by the physical or semantic properties of the stimuli. A model of response preparation is supported in which response inhibition depends upon the outcome of a race between independent excitatory and inhibitory processes, and reaction time is the sum of the durations of at least two stages, separated by the point of no return.

Choice Behavior↗
PubMed1980

Evaluation of a language program for young autistic children.

This report presents retrospective data comparing an individualized language development program for preschool autistic children receiving language remediation (experimental subjects) with a group receiving the basic school curriculum only (control subjects). All findings favored the language remediation group, as indicated: (1) experimental subjects made significant gains in one year while the control group required two years; (2) after one year, experimental subjects surpassed controls on four measures; (3) only experimental subjects made significant gains in communicative speech, noteworthy because interpersonal interaction is so difficult for the autistic child; and (4) after two years, 58% of the experimental subjects, but only 14% of the controls, had mastered all seven skills. These results support the hypothesis that an individualized language remediation program facilitates the acquisition of prelinguistic and linguistic skills.

Autistic Disorder↗