Parametric exploration of the Simon effect across visual space.

The Simon effect refers to the performance advantage for responding to the nonspatial identity of the target when the target's irrelevant location corresponds with the relative location of the response. The present study is a parametric examination of the magnitude of the Simon effect across visual space. Response keys were arranged along vertical, horizontal, and two diagonal axes, and stimuli were arranged in two concentric circles (near and far from fixation) along the same axes. The results show that the Simon effect is of similar magnitude regardless of stimulus-response axis. In contrast to findings from stimulus-response compatibility paradigms, there was no evidence in this study for the presence of an orthogonal compatibility effect or left-right prevalence effect, suggesting that these effects only arise when response location is relevant. The results demonstrate the robust generalizability of the Simon effect under different spatial conditions and thus broaden the relevance of the Simon effect to a variety of applications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal stimulus–response compatibility.

The study of element-level stimulus–response compatibility (SRC) has predominantly focused on spatial and symbolic relationships and has involved measures of response time and (dichotomous) error rate. This article explores a new form of SRC that is observed when duration is the relevant feature of both the stimulus and the response, using a more extensive analysis of performance accuracy and variability. The results indicate that element-level SRC generalizes to situations involving time as the relevant dimension of stimuli and responses. Evidence of this was found in all of the extracted measures of performance; however, temporal SRC was shown to have independent effects on when and how accurately a response was made. Implications for SRC research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of selective attention in the perception of multiple-element stimulus arrays.

To access the role of attention in visual processing, we have recorded single-unit activity from area V4 of visual cortex in macaque monkeys, and the results of these experiments provide a clear demonstration of the relationship between inter-stimulus competition and attention. Specifically, attended stimuli elicit larger responses than ignored stimuli, and these attention effects are increased when: a) the total number of distracting stimuli is increased; b) both attended and ignored stimuli are located inside the neuron's receptive field; and c) the attended and ignored stimuli are presented simultaneously rather than sequentially. We have also examined the role of inter-stimulus competition in human subjects by recording event-related potentials (ERPs), which are electrophysiological responses that can be recorded noninvasively from the scalp. In these experiments, we have found that the attention-sensitive N2pc wave is present when subjects focus attention onto target stimuli when they are surrounded by competing distractor stimuli, but is absent when the competition is eliminated (e.g. by removing the distractors). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Response-Discrimination Account of the Simon Effect.

Simon effects might partly reflect stimulus-triggered response activation. According to the response-discrimination hypothesis, however, stimulus-triggered response activation shows up in Simon effects only when stimulus locations match the top-down selected spatial codes used to discriminate between alternative responses. Five experiments support this hypothesis. In Experiment 1, spatial codes of each response differed by horizontal and vertical axis position, yet one axis discriminated between alternative responses, whereas the other did not. Simon effects resulted for targets on discriminating axes only. In Experiment 2, both spatial axes discriminated between responses, and targets on both axes produced Simon effects. In Experiment 3, Simon effects resulted for a spatial choice-reaction task but not for a go/no-go task. Even in the go/no-go task, a Simon effect was restored when a two-choice reaction task preceded the go/no-go task (Experiment 4) or when participants initiated trials with responses spatially discriminated from the go response (Experiment 5). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of visual stimulus mode on transfer of acquired spatial associations.

Associations between corresponding stimulus–response locations are often characterized as overlearned, producing automatic activation. However, 84 practice trials with an incompatible mapping eliminate the benefit for spatial correspondence in a transfer Simon task, where stimulus location is irrelevant. The authors examined whether transfer occurs for combinations of physical-location, arrow-direction, and location-word modes in the practice and transfer sessions. With 84 practice trials, the Simon effect was reduced for locations and arrows, and there was complete transfer across these modes; location words showed little transfer within or between modes. These results suggest that the acquired short-term associations were based on visual-spatial stimulus codes distinct from semantic-spatial codes activated by the words. With 600 practice trials, words showed transfer to word and arrow but not location Simon tasks, suggesting that arrows share semantic-spatial codes with words. Reaction-time distribution functions for the Simon effect showed distinct shapes for each stimulus mode, with little impact of the practiced mapping on the shapes. Thus, the contribution of the short-term location associations seems to be separate from that of the long-term associations responsible for the Simon effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of a subliminal food stimulus on verbal responses.

To what extent can subliminal stimulation be used to influence human behavior? This study involving 105 college freshmen attempts to isolate and study a few of the possible variables. "The experimental group saw a classroom movie with the word 'beef' superimposed in flashes of –1??? of a second every seven seconds; the control group just saw the movie. It was found that, compared to the control Ss, the experimental Ss (a) did not show increased verbal references to the stimulus word; (b) did not choose the stimulus object in a multiple choice situation (though sex differences were significant); but (c) did rate themselves significantly more hungry. It was also found that hours of food deprivation did not influence any of these relationships. 15 refs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A set of conditions for a consistent recovery of a subliminal stimulus.

3 experimental groups of 10 Ss, each with their corresponding controls, were given mathematical problems in a tachistoscope as a supraliminal stimulus. At a level established by a pretest group, the experimental groups received subliminal answers to the problems. Group 1 attempted to solve the problems, Group 2 to guess at the answers, and Group 3 to select their answers from dual possibilities on a given list. A significant tendency was found in Groups 1 and 2 to repeat various subliminally projected digits in their answers, without the answers directly affecting their computational processes. Group 3 selected the projected answers significantly over the correct answers. The need for a positive relationship between supra- and subliminal stimuli as well as the relevancy of the task to the Ss' present activity was also observed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of response task and accessory stimuli on redundancy gain: Tests of the hemispheric coactivation model.

Two experiments tested predictions of the hemispheric coactivation model for redundancy gain (J. O. Miller, 2004). Simple reaction time was measured in divided attention tasks with visual stimuli presented to the left or right of fixation or redundantly to both sides. Experiment 1 tested the prediction that redundancy gain--the decrease in reaction time when 2 stimuli are presented rather than 1--should increase when the response requires a greater degree of bilateral control by both hemispheres. In different blocks, the response was made with the left hand, the right hand, or both hands simultaneously. In accordance with the model, redundancy gain was larger with bimanual than with unimanual responses. Experiment 2 tested and found support for the prediction that redundancy gain should decrease when both hemispheres are activated by an irrelevant auditory accessory stimulus. Thus, the results support the hemispheric coactivation model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A reply to Mace and Pittenger on "Directly perceiving Gibson".

A reply to Mace and Pittenger on "Directly Perceiving Gibson" (see record 2005-09162-001). W. M. Mace and J. B. Pittenger address themselves to a false issue when they argue that J. J. Gibson has both a theory of stimulus structure and a theory of attention. The point of the 1972 article by J. W. Gyr is that these two theories are not as well integrated as they might be or as integrated as Gibson intended them to be. Moreover, a point also stressed by Gyr and overlooked by Mace and Pittenger is that Gibson's findings of stimulus structure are also consistent with theories that are not theories of direct visual perception, and therefore such findings by themselves cannot be used to support Gibson's theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic Aspects of Stimulus-Response Correspondence: Evidence for Two Mechanisms Involved in the Simon Effect.

It has been recently proposed that the time course of the Simon effect may vary across tasks, which might reflect different types of stimulus-response (S-R) transmissions (E. Wascher, U. Schatz, T. Kuder, & R. Verleger, 2001). The authors tested this notion in 4 experiments by comparing Simon effects evoked by horizontal and vertical S-R arrangements. The temporal properties of the effect, as well as lateralized readiness potential-difference waves, indicated a fast and transient influence of the horizontal, but a slow and sustained influence of the vertical spatial stimulus feature on performance. Additional evidence for this temporal dissociation was obtained in experiments that induced a shortening or lengthening of the mean response time. Thus, the data strongly indicate that there are 2 temporally dissociable mechanisms involved in generating the Simon effect for horizontal and vertical S-R relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modulating the interference effect in timing with varying stimulus onset asynchrony.

The interference effect on time judgments, when subjects are also required to perform a concurrent nontemporal task, is one of the most reliable findings in the time perception literature. In the present study, the interference between a time discrimination task (short or long tone) and a digit classification task (even or odd digit) was analysed using the overlapping tasks paradigm. Reaction times in the digit task were shorter at longer values of stimulus onset asynchrony (SOA) in Experiment 1, showing a clear modulation of interference with varying the relative position of the tasks. Using longer tone durations in Experiment 2, reaction times in the digit task were affected not only by the overlap between the tasks but also by the temporal proximity of responses in the timing and digit tasks. In Experiment 3, the effect of varying the SOA on performance on the digit task was abolished when the auditory tone was irrelevant, thus eliminating an interpretation in terms of distraction from the tone offset. We conclude that the interference effect in concurrent time discrimination and digit classification may be modulated by the degree of overlap between the tasks as well as by the overlap between late processing stages related to decision and response components in the 2 tasks. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Does irrelevant stimulus location affect response selection?

Reaction time (RT) is shorter when the irrelevant location of the stimulus corresponds to the relevant location of the response: When a subject is to perform a left or right keypress according to the colour of a stimulus delivered either to the left or to the right of a fixation, RT is typically shorter when the location of the stimulus corresponds to the location of the response (e.g., left stimulus/left response) than when it does not (e.g., left stimulus/right response). Umiltà and Nicoletti (1990) have suggested that this effect, known as the ?Simon effect' in the literature, occurred at the response selection stage, a stage whose duration depends on the effectors used to perform the task. In the present study, this effect and that of the finger response repertoire (within- versus between-hand composition) were found to be additive, which does not support the response selection hypothesis of the Simon effect.     

The impact of stimulus and response variability on S-R correspondence effects.

Six experiments investigated how variability on irrelevant stimulus dimensions and variability on response dimensions contribute to spatial and nonspatial stimulus-response (S-R) correspondence effects. Experiments 1-3 showed that, when stimuli varied in location and number, S-R correspondence effects for location or numerosity occurred when responses varied on these dimensions but not when responses were invariant on these dimensions. These results are consistent with the response-discrimination account, according to which S-R correspondence effects should only arise for a dimension that is used for discriminating between responses in working memory. Experiments 4-6 showed that, when responses varied in location and number, both invariant and variable stimulus number produced correspondence effects in S-R numerosity. In summary, the present results indicate that the usefulness of a particular dimension for response discrimination can be sufficient for producing S-R correspondence effects, whereas variability of a stimulus dimension is not sufficient for producing such effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the uniqueness of attentional capture by uninformative gaze cues: Facilitation interacts with the Simon effect and is rarely followed by IOR.

Orienting to an uninformative peripheral cue is characterized by a brief facilitation followed by a long-lasting inhibition once attention is removed from the cued location. Although central gaze cues cause reflexive orienting, the inhibitory effect that is relatively ubiquitous following exogenous orienting to uninformative peripheral cues has been relatively rare. We hypothesized that IOR might be seen following gaze-induced orienting if attention were effectively returned to centre by a return gaze or return flash. The timecourse of gaze-directed orienting was measured by varying the interval between the gaze cue and a peripheral target requiring an orientation discrimination (permitting measurement of the Simon effect). Significant facilitation was observed at all but the longest SOA tested, 2,880 ms, by which time the facilitation had disappeared with no evidence of IOR. Gaze-induced cuing (which was unaffected by return cue condition) interacted with the Simon effect, decreasing it at the gazed-at location, a pattern that is not seen with more typical endogenous and exogenous cuing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of object onset on the distribution of visual attention.

There now exists considerable evidence to suggest that the appearance of a new object in the visual field captures visual attention. One of the consequences of this attentional capture is that the object initiates a redistribution of attentional resources across visual space. This is classically observed in the precuing paradigm in which the onset of an abrupt cue influences the processing of a subsequently presented target. The present research describes a new phenomenon that occurs as a result of a new object appearing in the visual field. A stimulus presented in a region of space adjacent to a comer of an onsetting object receives an enhancement of processing relative to a stimulus presented adjacent to one of the object's straight edges. With the use of 2 converging methods, evidence is presented that suggests that the effect is a higher order attentional phenomenon whereby greater resources become directed to the comers of objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of aversive stimuli on reaction time in schizophrenia.

"… the experiment was to assess the motivational role of aversive stimuli in modifying the performance of normal and… schizophrenic… males… [on] a visual reaction time task… . During… [one] series Ss responded under… experimental conditions… [part of which] involved the use of intense noise as an aversive stimulus. None of the experimental conditions appreciably altered the performance of normal Ss. However, schizophrenic Ss performing under… [conditions involving noise] displayed greater improvement than control Ss." 22 refs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control over location-based response activation in the Simon task: Behavioral and electrophysiological evidence.

In 4 Simon experiments the authors examined control over 2 routes of sensorimotor processing: response priming in the unconditional route and response selection via the conditional route. The Simon effect diminished as the frequency of noncorresponding trials increased. Location-based response priming was observed only when the stimulus followed a corresponding event but not after a noncorresponding trial. Therefore, the unconditional route appears to be suppressed whenever the task context indicates priming as potentially disadvantageous. Moreover, the task-irrelevant stimulus location was used for response selection as a function of correspondence probability. Although exact repetitions of stimulus-response sequences caused a marked speed-up of responses, this 3rd mechanism is independent of unconditional route suppression and frequency-based adjustments in the conditional route. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intrahemispherical activation, visuomotor transmission, and the Simon effect: Comment on Wascher et al. (2001).

On the basis of 3 experiments, E. Wascher, U. Schatz, T. Kuder, and R. Verleger (2001; see record 2001-06699-017) concluded, "The variety of tasks subsumed under the term Simon effect turned out to be heterogeneous" (p. 749). This comment critically evaluates the validity of their conclusion by considering their hypotheses, methodology, specific conclusions, and proposed broader implications. Although the Simon effect is a behavioral phenomenon, E. Wascher et al. relied heavily on physiology in hypothesis generation, methodology, and interpretation of results. Moreover, methodological differences from most previous studies, combined with limited statistical support, nonreplication of previously reported behavioral phenomena, inconsistencies in results across experiments, and evidence against a contribution of intrahemispherical activation by visuomotor pathways, strongly suggest that their conclusion should be viewed with caution. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The subliminal mere exposure effect does not generalize to structurally related stimuli.

R. F. Bornstein (1994) questioned whether subliminal mere exposure effects might generalize to structurally related stimuli, thereby providing evidence for the existence of implicit learning. Two experiments examined this claim using letter string stimuli constructed according to the rules of an artificial grammar. Experiment 1 demonstrated that brief, masked exposure to grammatical strings impaired recognition but failed to produce a mere exposure effect on novel structurally related strings seen at test. Experiment 2 replicated this result but also demonstrated that a reliable mere exposure effect could be obtained, provided the same grammatical strings were presented at test. The results suggest that the structural relationship between training and test items prevents the mere exposure effect when participants are unaware of the exposure status of stimuli, and therefore provide no evidence for the existence of implicit learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hemispheric asymmetries for global and local visual perception: Effects of stimulus and task factors.

Although neurological and physiological studies indicate a right hemisphere superiority in global processing and a left hemisphere superiority in local processing of Navon-type hierarchical letters (D. Navon, 1977), most investigations of lateralized perception in healthy participants report neither asymmetry. In 6 experiments the authors examined the influence of attentional demands, stimulus properties, and mode of response on perceptual asymmetries for global and local perception. Consistent with their theoretical predictions, asymmetries were more robust on divided- than focused-attention tasks and in response to stimuli in which local and global levels were equally salient compared with those with greater global than local saliency. Contrary to their prediction, perceptual asymmetries were not influenced by the complexity of the motor response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)