Validity and boundary conditions of automatic response activation in the Simon task.

Three experiments were conducted to determine whether spatial stimulus-response compatibility effects are caused by automatic response activation by stimulus properties or by interference between codes during translation of stimulus into response coordinates. The main evidence against activation has been that in a Simon task with hands crossed, responses are faster at the response location ipsilateral to the stimulus though manipulated by the hand contralateral to the stimulus. The experiments were conducted with hands in standard and in crossed positions and electroencephalogram measures showed coactivation of the motor cortex induced by stimulus position primarily during standard hand positions with visual stimuli. Only in this condition did the Simon effect decay with longer response times. The visual Simon effect appeared to be due to specific mechanisms of visuomotor information transmission that are not responsible for the effects obtained with crossed hands or auditory stimuli. (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)     

Temporary activation of perceptual–motor associations: A stimulus–response interpretation of automaticity.

Some types of automaticity can be attributed to simple stimulus–response associations (G. D. Logan, 1988). This can be studied with paradigms in which associations to an irrelevant stimulus automatically influence responding to a relevant stimulus. In 1 example, the irrelevant and relevant stimuli were presented successively with the 1st, irrelevant, stimulus masked. Although this stimulus was not phenomenally visible, it influenced responding to the 2nd, visible, stimulus. This influence was substantial only if associations to the 1st stimulus had been activated by recent responding (S. T. Klapp & B. W. Haas, 2005). These associations were not processed deeply; instead, they only relate specific stimuli to specific responses. Whereas these conclusions were demonstrated previously with masking so that participants were not aware of the irrelevant stimulus and thus had no basis to permit control of its influence, the present research demonstrated the same principles when all stimuli were visible. Furthermore, activation of the associations was not subject to substantial intentional control. These findings imply that association-based automaticity occurs independently of, and uninfluenced by, awareness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Count me in! On the automaticity of numerosity processing.

Extraction of numerosity (i.e., enumeration) is an essential component of mathematical abilities. The current study asked how automatic is the processing of numerosity and whether automatic activation is task dependent. Participants were presented with displays containing a variable number of digits and were asked to pay attention to the number of digits or to their numerical value, in separate blocks. Effects of task were tested with a comparative judgment task and a parity judgment task. In the comparative judgment task, participants had to indicate whether the numerosity or the numerical value of the digits was smaller or larger than 5. In the parity judgment task, participants had to indicate whether this value was odd or even. Irrelevant numerical values modulated performance regardless of task. In contrast, irrelevant numerosities modulated performance only in the comparative judgment task. These results suggest that numerical value is activated automatically, whereas activation of numerosity is modulated by task. We suggest that the differences observed are related to different cognitive and neural mechanisms recruited by these tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beyond behaviorism: On the automaticity of higher mental processes.

The first 100 years of experimental psychology were dominated by 2 major schools of thought: behaviorism and cognitive science. Here the authors consider the common philosophical commitment to determinism by both schools, and how the radical behaviorists' thesis of the determined nature of higher mental processes is being pursued today in social cognition research on automaticity. In harmony with "dual process" models in contemporary cognitive science, which equate determined processes with those that are automatic and which require no intervening conscious choice or guidance, as opposed to "controlled" processes which do, the social cognition research on the automaticity of higher mental processes provides compelling evidence for the determinism of those processes. This research has revealed that social interaction, evaluation and judgment, and the operation of internal goal structures can all proceed without the intervention of conscious acts of will and guidance of the process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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)     

The role of long-term-memory and short-term-memory links in the Simon effect.

In Experiment 1, children performed a Simon task after a spatially compatible or incompatible task. Results showed a Simon effect after the spatially compatible task and a reversed Simon effect after the spatially incompatible task. In Experiments 2–5, an identical procedure was adopted with adult participants, who performed the Simon task immediately after, a day after, or a week after the spatial compatibility task. Experiment 6 established a baseline for the Simon effect. Results showed a Simon effect after the spatially compatible task and no Simon effect or a reversed Simon effect after the spatially incompatible task. A modified version of the computational model of M. Zorzi and C. Umiltà (1995) was used to compare possible accounts of the findings. The best account exploits 2 types of short-term-memory links between stimulus and response and their interaction with long-term-memory links. (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)     

Priming processes in the Simon task: More evidence from the lexical decision task for a third route in the Simon effect.

Recently, it was proposed that the Simon effect would result not only from two interfering processes, as classical dual-route models assume, but from three processes. It was argued that priming from the spatial code to the nonspatial code might facilitate the identification of the nonspatial stimulus feature in congruent Simon trials. In the present study, the authors provide evidence that the identification of the nonspatial information can be facilitated by the activation of an associated spatial code. In three experiments, participants first associated centrally presented animal and fruit pictures with spatial responses. Subsequently, participants decided whether laterally presented letter strings were words (animal, fruit, or other words) or nonwords; stimulus position could be congruent or incongruent to the associated spatial code. As hypothesized, animal and fruit words were identified faster at congruent than at incongruent stimulus positions from the association phase. The authors conclude that the activation of the spatial code spreads to the nonspatial code, resulting in facilitated stimulus identification in congruent trials. These results speak to the assumption of a third process involved in the Simon task. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Simon effect with and without awareness of the accessory stimulus.

The authors investigated whether a Simon effect could be observed in an accessory-stimulus Simon task when participants were unaware of the task-irrelevant accessory cue. In Experiment 1A a central visual target was accompanied by a suprathreshold visual lateral cue. A regular Simon effect (i.e., faster cue-response corresponding reaction times [RTs]) was found. Experiment 1B demonstrated that this effect cannot be attributed to perceptual grouping of the target and cue. Experiments 2A, 2B, and 2C showed a reverse Simon effect (i.e., faster noncorresponding RTs) when participants were not aware of the cue. In this condition, the Simon effect would occur relative to the reorientation of attention from the cue, which would initially capture attention, toward the target. This conclusion is supported by the results of Experiments 3A and 3B, in which the reorientation of attention was induced by having the target flash after its onset. With suprathreshold cues either a reverse or regular Simon effect was observed by using a 100-ms or ≥200-ms onset flashing interval, respectively, whereas with subthreshold cues a reverse Simon effect was found irrespective of the interval length. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ethanol effect on activation and maintenance of cold stress response in immature rats

Rats at thermoneutral ambient temperature (Ta) exhibit change in thermoregulatory response to ethanol (EtOH) from 2 to 15 days of age. In the present study, rats at 2-3, 8-9, and 14-15 days of age were administered either saline or EtOH (4 g/kg b.wt.;IP) using two different routines to determine EtOH effect on specific cold defense mechanisms. Injection of EtOH in the first routine occurred after exposure to cold Ta, to determine effect on maintenance of cold thermogenesis. EtOH-induced metabolic depression increased from 3 to 8 days of age, with little change after this time. Injection of EtOH in the second routine was at thermoneutral Ta, followed at 20 min postinjection by rapid exposure to cold Ta to determine effect on activation of cold thermogenesis. EtOH-treatment delayed onset of cold thermogenesis at 2-3 and 14-15 days of age, and completely eliminated 8-9-day-old response to cold Ta. Rats exposed to cold Ta at 2-3 days of age exhibited a slower rate of EtOH absorption and lower blood EtOH concentration than rats in the older groups, to explain some age differences in EtOH response.     

Stimulus-response compatibility and the Simon effect: Toward an empirical clarification.

Perceptual accounts attribute the Simon effect to the correlation between relevant stimulus feature and response location (e.g., T. Hasbroucq & Y. Guiard, 1991). This account is questioned, and it is demonstrated that a Simon effect can be obtained without a stimulus–response correlation (Experiment 1). Experiments 2 and 3 replicated this finding and showed that the relative size of stimuli and response labels and temporal overlap of warning signal and stimulus cannot account for why the effect was absent in Hasbroucq and Guiard's study. However, no Simon effect occurred in a close replication of Hasbroucq and Guiard's original experiment (Experiment 4). Participants' reports suggested that this was due to a special stimulus-coding strategy, and in fact, the effect reappeared with a slightly modified stimulus display (Experiment 5). These results provide strong evidence against a perceptual approach to the Simon effect and support response-related views instead. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory-based automaticity in the discrimination of visual numerosity.

In the development of memory-based models of automaticity, it is crucial to specify the nature of the memory representation. Seven experiments with 94 students use a counting task to determine whether a feature (i.e., identity, color, or orientation) is explicitly represented in memory. It is assumed that the degree of transfer to a pattern differing on one feature is determined by that feature's importance in supporting skilled performance. Exp 1 determined the practice necessary to obtain automaticity. In Exps 2a, 3a, and 4a, which investigated the nature of the representation after extended practice, changing neither the identity nor color of elements had strong effects on transfer, but changing pattern orientation did impair memory retrieval, thus suggesting that for the counting task, pattern orientation is more important than element identity or color. Exps 2b, 3b, and 4b replicated these results after limited practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exemplar similarity and the development of automaticity

Effects of exemplar similarity on the development of automaticity were investigated with a task in which participants judged the numerosity of random patterns of between 6 and 11 dots. After several days of training, response times were the same at all levels of numerosity, signaling the development of automaticity. In Experiment 1, response times to new patterns were a function of their similarity to old patterns. In Experiment 2, responses to patterns with high within-category similarity became automatized more quickly than responses to patterns with low within-category similarity. In Experiment 3, responses to patterns with high between-category similarity became automatized more slowly than responses to patterns with low between-category similarity. A new theory, the exemplar-based random walk (EBRW) model, was used to explain the results. Combining elements of G. D. Logan's (1988) instance theory of automaticity and R. M. Nosofsky's (1986) generalized context model of categorization, the theory embeds a dynamic similarity-based memory retrieval mechanism within a competitive random walk decision process.     

The Simon effect occurs relative to the direction of an attention shift.

We investigated whether the Simon effect depends on the orienting of attention. In Experiment 1, participants were required to execute left-right discriminative responses to 2 patterns that were presented to the left or right of fixation. The 2 patterns were similar, and the discrimination was difficult. A letter at fixation signaled whether the current trial was a catch trial. The results showed a reversal of the Simon effect. That is, spatially noncorresponding responses were faster than spatially corresponding responses. In Experiment 2, the discrimination of the relevant stimulus attribute was easy. In Experiment 3, the discrimination of the relevant stimulus attribute was difficult, but the stimulus exposure time was long. In either experiment, the regular Simon effect was reinstated. In Experiment 4, the letter that signaled a catch trial appeared to the left or right of the imperative stimulus. The Simon effect occurred relative to the position of the letter. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention in the acquisition and expression of automaticity.

The instance theory of automaticity claims that people learn what they attend to and express what they learned in transfer if they attend to the same things in the same was. These hypotheses were tested in 8 category search experiments in which target position was cued by color (red or green). The main question was whether target color would be encoded in training and retrieved in transfer. After training, recognition memory for target color was above chance, which suggests that color was encoded. However, category search performance was not affected by changing target color unless color was reported explicitly during training and transfer, which suggests that color was not always retrieved. The results are consistent with the instance theory. The distinction between encoding and retrieval is important in understanding the acquisition and expression of automaticity. Automatic performance emphasized speed and so may not be sensitive to things that are retrieved slowly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging and the development of automaticity in visual search.

The rate of short-term memory search has previously been reported to be slower for older individuals than for college-age Ss (F. I. Craik, 1977). Current research has suggested that after extensive practice with the same population of stimuli, performance in memory-search and visual-search tasks can become "automatic," or independent of memory load. The present experiment examined age differences in the development of automatic processing in a hybrid memory-search/visual-search paradigm; 8 young (18–25 yrs old) and 8 older (61–74 yrs old) Ss participated. Although older Ss demonstrated a significantly slower rate of search, the 2 age groups shifted toward automatic processing, over practice, at equivalent rates. The slower rate of search thus represents an age-related increase in the time required to compare the memory-set items against those in a visual array, rather than a change in the mode of processing available. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention and automaticity in the processing of self-relevant information.

Studied the neglected aspect of social cognition: the way people select information for further processing from the vast amount available in social environments. A dichotic listening task was used in which 141 undergraduate Ss attended to or ignored self-relevant stimuli. It was found that self-relevant information required fewer attentional resources when presented to the attended channel, but more when presented to the rejected channel, relative to neutral words. This differential capacity allocation occurred despite Ss' lack of awareness of the contents of the rejected channel. Results support the existence and interaction of the 2 processes of attention in social information processing: a control process that regulates the contents of conscious awareness and an automatic process that attracts attention to stimuli without conscious intent. (70 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Trial-to-trial modulations of the Simon effect in conditions of attentional limitations: Evidence from dual tasks.

Interference effects are reduced after trials including response conflict. This sequential modulation has often been attributed to a top-down mediated adaptive control mechanism and/or to feature repetition mechanisms. In the present study we tested whether mechanisms responsible for such sequential modulations are subject to attentional limitations under dual-task situations. Participants performed a Simon task in mixed single- and dual-task contexts (Experiment 1), in blocked contexts with dual-task load either, in trialN (Experiment 2a), in trialN – 1 (Experiment 2b), or in both trials (Experiment 3). Results showed that the occurrence of a sequential modulation did not depend on dual-task load per se as it occurred predominantly in conditions of lowest and highest task load. Instead, task factors such as the repetition of task episodes and stimulus-response repetitions determined whether a sequential modulation occurred. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mosquito-Plasmodium interactions in response to immune activation of the vector

A molecular model was built for human lecithin:cholesterol acyltransferase (LCAT) based upon the structural homology between this enzyme and lipases (Peelman et al. 1998. Prot. Sci. 7: 585-597). We proposed that LCAT belongs to the alpha/beta hydrolase fold family, and that the central domain of LCAT consists of a mixed seven-stranded beta-pleated sheet with four alpha-helices and loops linking the beta-strands. The catalytic triad of LCAT was identified as Asp345 and His377, as well as Ser181. This model is used here for the interpretation of the structural defects linked to the point mutations identified in LCAT, which cause either familial LCAT deficiency (FLD) or fish-eye disease (FED). We show that these mutations occur in separate domains of the 3D structure of the enzyme. Most mutations causing familial LCAT deficiency are either clustered in the vicinity of the catalytic triad or affect conserved structural elements in LCAT. Most mutations causing fish-eye disease are localized on the outer hydrophilic surface of the amphipathic helical segments. These mutations affect only minimally the overall structure of the enzyme, but are likely to impair the interaction of the enzyme with its co-factor and/or substrate.