Enhanced spatial stimulus–response mapping near the hands: The Simon effect is modulated by hand-stimulus proximity.

2014 ◽  
Vol 40 (6) ◽  
pp. 2252-2265 ◽  
Author(s):  
Xiaotao Wang ◽  
Feng Du ◽  
Xiaosong He ◽  
Kan Zhang
2018 ◽  
Author(s):  
Motonori Yamaguchi ◽  
Jing Chen

The present study examined the effect of stimulus valence on two levels of selection in the cognitive system, selection of a task-set and selection of a response. In the first experiment, participants performed a spatial compatibility task (pressing left and right key according to the locations of stimuli) in which stimulus-response mappings were determined by stimulus valence. There was a standard spatial stimulus-response compatibility (SRC) effect for positive stimuli (flowers) and a reversed SRC effect for negative stimuli (spiders), but the same data could be interpreted as showing faster responses when positive and negative stimuli were assigned to compatible and incompatible mappings, respectively, than when the assignment was opposite. Experiment 2 disentangled these interpretations, showing that valence did not influence a spatial SRC effect (Simon effect) when task-set retrieval was unnecessary. Experiments 3 and 4 replaced keypress responses with joystick deflections that afforded approach/avoidance action coding. Stimulus valence modulated the Simon effect (but did not reverse it) when the valence was task-relevant (Experiment 3) as well as when it was task-irrelevant (Experiment 4). Therefore, stimulus valence influences task-set selection and response selection, but the influence on the latter is limited to conditions where responses afford approach/avoidance action coding.


Author(s):  
Luisa Lugli ◽  
Stefania D’Ascenzo ◽  
Roberto Nicoletti ◽  
Carlo Umiltà

Abstract. The Simon effect lies on the automatic generation of a stimulus spatial code, which, however, is not relevant for performing the task. Results typically show faster performance when stimulus and response locations correspond, rather than when they do not. Considering reaction time distributions, two types of Simon effect have been individuated, which are thought to depend on different mechanisms: visuomotor activation versus cognitive translation of spatial codes. The present study aimed to investigate whether the presence of a distractor, which affects the allocation of attentional resources and, thus, the time needed to generate the spatial code, changes the nature of the Simon effect. In four experiments, we manipulated the presence and the characteristics of the distractor. Findings extend previous evidence regarding the distinction between visuomotor activation and cognitive translation of spatial stimulus codes in a Simon task. They are discussed with reference to the attentional model of the Simon effect.


Neuroreport ◽  
2001 ◽  
Vol 12 (5) ◽  
pp. 973-977 ◽  
Author(s):  
Alessandro Angrilli ◽  
Marco Zorzi ◽  
Mariaelena Tagliabue ◽  
Luciano Stegagno ◽  
Carlo Umiltà

2010 ◽  
Vol 103 (5) ◽  
pp. 2664-2674 ◽  
Author(s):  
Joonkoo Park ◽  
Jun Zhang

A study in 2002 using a random-dot motion-discrimination paradigm showed that an information accumulation model with a threshold-crossing mechanism can account for activity of the lateral intraparietal area (LIP) neurons. Here, mathematical techniques were applied to the same dataset to quantitatively address the sensory versus motor representation of the neuronal activity during the time course of a trial. A technique based on Signal Detection Theory was applied to provide indices to quantify how neuronal firing activity is responsible for encoding the stimulus or selecting the response at the behavioral level. Additionally, a statistical model based on Poisson regression was used to provide an orthogonal decomposition of the neural activity into stimulus, response, and stimulus-response mapping components. The temporal dynamics of the sensorimotor locus of the LIP activity indicated that there is no stimulus-response mapping-specific neuronal firing activity throughout a trial; the neural activity toward the saccadic onset reflects the development of the motor representation, and the neural activity in the beginning of a trial contains little, if any, information about the sensory representation. Sensorimotor analysis on individual neurons also showed that the neuronal activation, as a population, represent pending saccadic direction and carry little information about the direction of the motion stimulus.


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