A Simon effect for stimulus-response duration

A non-spatial variant of the Simon effect for the stimulus-response (S-R) feature of duration is reported. In Experiment 1 subjects were required to press a single response key either briefly or longer in response to the colour of a visual stimulus that varied in its presentation duration. Short keypresses were initiated faster with short than with long stimulus duration whereas the inverse was observed with long keypresses. In Experiment 2 subjects were required to press a left or right key (according to stimulus form) either briefly or longer (according to stimulus colour). The stimuli concurrently varied in their location (left or right) and duration (short or long), which were both task irrelevant. Approximately additive correspondence effects for S-R location and S-R duration were observed. To summarize, the results suggest that the irrelevant stimulus features of location and duration are processed automatically and prime corresponding responses in an independent manner.     

Effect of compatibility of S-R mapping on reactions toward the stimulus source

This research was concerned with separating the effects of three varieties of S-R compatibility: reactions toward the stimulus source, compatibility of S-R mapping, and display-control arrangement correspondence. In experiments 1 and 2, subjects pressed a green or red key located on the left and right in response to the onset of a green or red stimulus presented in a left or right window. Half of the subjects pressed the key which corresponded to the color of the stimulus (compatible S-R mapping) while the other half pressed the alternate colored key (incompatible S-R mapping). In the compatible mapping task, reactions were faster when location of stimulus and response corresponded than when they did not while, in the incompatible task, reactions were faster when location of stimulus and response did not correspond. This apparent reversal in the tendency to react toward the stimulus source was attributed to display- control arrangement correspondence rather than to logical recoding of the directional cue. Experiment 3 established that faster reactions toward the stimulus source occured only under compatible mapping instructions.     

Must egocentric and environmental frames of reference be aligned to produce spatial S-R compatibility effects?

Four experiments were conducted to determine the effects of misaligning egocentric and environmental frames of reference on spatial S-R compatibility effects. In Experiments 1 and 3, subjects looked at two lights that were aligned horizontally, one each on either side of the body midline. They held their head upright or tilted 90 degrees to the left or right. In the upright condition the hands were uncrossed and rested opposite the lights (frames of reference aligned), whereas in the head tilt condition the hands were either crossed or uncrossed but positioned perpendicular to the lights (frames of reference not aligned). Manual choice reaction times to the lights produced spatial S-R compatibility effects that were as large when the frames of reference were aligned as when they were not. In Experiments 2 and 4, which also used upright and tilted conditions, we found generally similar results when the lights were displayed vertically and the hands disposed horizontally. The results indicate that under conditions of head rotation and with stimulus and response arrays perpendicular to each other, spatial S-R compatibility effects still occur. By taking into account both frames of reference, the subject classifies the stimuli as left or right whether they are horizontally or vertically disposed and maps them onto the responding hand, thereby producing the observed compatibility effects.     

Stimulus control of free-operant avoidance: The contribution of response rate and incentive relations between multiple-schedule components

The associations formed in the components of a multiple schedule can be classified as (1) stimulus-response (S-R) associations and (2) stimulus-reinforcer (S-S^R) associations. The present experiments sought to determine the individual contribution of these S-R and S-S^R associations to stimulus control by manipulating them independently. Responses postponed shocks by 25 sec in the presence of a tone alone and a light alone in all experiments. The contingencies programmed in the absence of both tone and light established a reference for the S-R and S-S^R associations in tone and in light. All four possible combinations of signalling response increase or decrease together with incentive increase or decrease were studied. Although the influence of the contingencies operating in the absence of tone and light was difficult to detect from response rates in tone or light, presenting tone and light together revealed clear effects. Response rates in tone and light together relative to those in either alone depended upon the contingency operating in the absence of tone and light. Stimulus-response and stimulus-reinforcer associations appeared to counteract each other when in opposition and combine together to enhance each other when in agreement. This suggested that the associations of a stimulus to response and to incentive combine algebraically in determining stimulus control. An algebraic analysis in terms of the S-R and S-S^R associations conditioned to the stimulus elements comprising the training and test stimuli accounted for the observed patterns of data.     

Is automatic imitation a specialized form of stimulus–response compatibility? Dissociating imitative and spatial compatibilities

In recent years research on automatic imitation has received considerable attention because it represents an experimental platform for investigating a number of interrelated theories suggesting that the perception of action automatically activates corresponding motor programs. A key debate within this research centers on whether automatic imitation is any different than other long-term S-R associations, such as spatial stimulus-response compatibility. One approach to resolving this issue is to examine whether automatic imitation shows similar response characteristics as other classes of stimulus-response compatibility. This hypothesis was tested by comparing imitative and spatial compatibility effects with a two alternative forced-choice stimulus-response compatibility paradigm. The stimulus on each trial was a left or right hand with either the index or middle finger tapping down. Speeded responses were performed with the index or middle finger of the right hand in response to the identity or the left-right spatial position of the stimulus finger. Two different tasks were administered: one that involved responding to the stimulus (S-R) and one that involved responding to the opposite stimulus (OS-R; i.e., the one not presented on that trial). Based on previous research and a connectionist model, we predicted standard compatibility effects for both spatial and imitative compatibility in the S-R task, and a reverse compatibility effect for spatial compatibility, but not for imitative compatibility, in the OS-R task. The results from the mean response times, mean percentage of errors, and response time distributions all converged to support these predictions. A second noteworthy result was that the recoding of the finger identity in the OS-R task required significantly more time than the recoding of the left-right spatial position, but the encoding time for the two stimuli in the S-R task was equivalent. In sum, this evidence suggests that the processing of spatial and imitative compatibility is dissociable with regard to two different processes in dual processing models of stimulus-response compatibility.     

Unconscious priming according to multiple S-R rules

The present study investigated if unconscious primes can be processed according to different stimulus-response (S-R) rules simultaneously. Participants performed two different S-R rules, such as judging a digit as smaller or larger than five and judging a letter as vowel or consonant. These S-R rules were administered in random order and announced by a previously presented cue. Each target stimulus was preceded by subliminal primes which afforded a different or an identical response according to either the currently irrelevant or currently relevant S-R rule. In three experiments, we consistently found priming effects according to currently irrelevant S-R rules, even when primes for the relevant and irrelevant S-R rules were presented simultaneously. Thus, unconscious stimuli have the power to activate responses according to currently required and currently not required S-R rules concurrently. The results are in line with response activation accounts of subliminal priming and suggest that at least two routes may gain access on response processes simultaneously.     

S-R associations, their extinction, and recovery in an animal model of anxiety: a new associative account of phobias without recall of original trauma

Associative accounts of the etiology of phobias have been criticized because of numerous cases of phobias in which the client does not remember a relevant traumatic event (i.e., Pavlovian conditioning trial), instructions, or vicarious experience with the phobic object. In three lick suppression experiments with rats as subjects, we modeled an associative account of such fears. Experiment 1 assessed stimulus-response (S-R) associations in first-order fear conditioning. After behaviorally complete devaluation of the unconditioned stimulus, the target stimulus still produced strong conditioned responses, suggesting that an S-R association had been formed and that this association was not significantly affected when the outcome was devalued through unsignaled presentations of the unconditioned stimulus. Experiments 2 and 3 examined extinction and recovery of S-R associations. Experiment 2 showed that extinguished S-R associations returned when testing occurred outside of the extinction context (i.e., renewal) and Experiment 3 found that a long delay between extinction and testing also produced a return of the extinguished S-R associations (i.e., spontaneous recovery). These experiments suggest that fears for which people cannot recall a cause are explicable in an associative framework, and indicate that those fears are susceptible to relapse after extinction treatment just like stimulus-outcome (S-O) associations.     

Stimulus congruence and the Simon effect

Summary A standard experimental procedure was implemented with novel response requirements to assess the hypothesis that the Simon effect is attributable not to the irrelevant stimulus-response relationship, but to the congruence between stimulus attributes. The stimulus ensemble consisted of the words LEFT and RIGHT, one of which was presented on each trial to the left or right of a central fixation point. The distinctive feature of the task is that subjects were asked to respond, by laterally placed keys, whether or not the stimulus word was in accord (i. e., congruent) with its location on the display. Asking subjects to judge stimulus congruence directly enables the effect of congruence to be assessed, as well as independent estimates of the two irrelevant S-R relationships that apply in the task — that is, between the response location and (1) the stimulus location (the Simon effect) and (2) the stimulus word (the reverse Simon effect). Marked effects were obtained in all three cases. Stimulus congruence remains in contention as a factor in the explanation of the Simon effect, but the strong effects of irrelevant S-R factors suggest that a more comprehensive account of the Simon effect is needed. An explanation in terms of stimulus salience, based on an interactive activational model, is briefly discussed.     

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.     

The attribution of friendliness

A study was conducted to explore attributions of friendliness resulting from live interaction. Subjects had either one or two encounters with a confederate whose behavior in each encounter was either friendly or unfriendly and was either spontaneous or forced by role requirements. Single encounter subjects formed impressions of the confederate that reflected the friendliness or unfriendliness of the confederate's behavior but these impressions were not modified by their knowledge that the confederate's behavior was freely chosen or forced. The same was true for subjects who had two friendly or two unfriendly interactions with the confederate. Subjects who found the confederate to be friendly in one encounter and unfriendly in the other formed impressions that took into account the causes of the confederate's behaviors. In general, these subjects modified their impressions according to the cause of the confederate's behavior in the second encounter.     

A role for set in the control of automatic spatial response activation

Spatial stimulus-response (S-R) compatibility effects are widely assumed to reflect the automatic activation of a spatial response by the spatial attributes of a stimulus. The experiments reported here investigate the role of the participant's set in enabling or interacting with this putatively automatic spatial response activation. Participants performed a color discrimination task (Experiment 1) or a localization task (Experiment 2). In each experiment, two different S-R mappings were used and a task-cue indicated the appropriate mapping on each trial. S-R compatibility and the time between the task-cue and target were manipulated, and compatibility effects were assessed as a function of (a) the time between the task-cue and the stimulus, and (b) whether the S-R mapping repeated or switched on consecutive trials. Critically, whether response mappings repeated or switched on consecutive trials determined the relation between compatibility effects and the time between task-cue and stimulus. These results are discussed in terms of an interaction between automatic spatial response activation and the participant's set.     

Selective effects of barbiturate and amphetamine on information processing and response execution

In a 3 × 2 × 2 factoral experiment, 12 subjects carried out a choice reaction task with reaction time (RT) and movement time (MT) as response measures.Independent variables were drug treatment (amphetamine, barbiturate, placebo), visual stimulus degradation and S-R compatibility. Visual stimulus degradation and S-R compatibility showed additive effect on the RT, but did not affect the MT. This confirms that stimulus encoding, response selection and response execution represent independent processing stages. The two drugs had selective effects on the RT and the MT. Barbiturate (as compared to placebo) had no effect on the MT, but it lengthened the RT, and this effect was additive with the effects of S-R compatibility but showed an interaction with the effects of stimulus degradation. Amphetamine (as compared to placebo) shortened the MT, but there was no significant main effect of amphetamine on the RT although the interaction with the effect of S— compatibility was significant. These results suggest that barbiturate affects stimulus encoding whereas amphetamine affects response-related processes..     

Cross-talk of instructed and applied arbitrary visuomotor mappings

Humans are able to perform any voluntary motor response to any environmental stimulus. This cornerstone of the flexibility of human behaviour has been investigated under the label of arbitrary visuomotor mapping. The focus of research has been the question as to how these mappings are executed once the subjects have been instructed appropriately. However, one question has been rather neglected thus far: what, in the first place, enables humans to instantaneously implement any arbitrary S-R mapping by mere instruction! We report an experiment assessing the cross-talk of arbitrary S-R mappings as a part of the instructed task representation, on the one hand, and the cross-talk of repetitively applied mappings, on the other hand. The results show a behavioural dissociation of the cross-talk elicited by instructed and applied mappings, suggesting that the first occurs on the level of task-set, whereas the latter occurs on the level of specific S-R associations.     

Sequential priming is not constrained by the shape of long-term learning curves

When multiple stimulus-to-response (S-R) mappings are randomly intermixed and repeated in a block of trials, immediate repetitions of an aspect of a stimulus and/or a response can facilitate stimulus detection, classification, and/or response selection--known as sequential priming. In addition to these short-term effects, response times (RT) for almost any task diminish with extended practice, improvements can occur over many days, and RT learning curves typically assume exponential or power functions. We investigated whether short-term sequential priming and long-term practice modulate RT through a common mechanism, using a variant of the additive factors method. We tracked how various priming effects, presumably affecting different processing stages (e.g, stimulus selection, stimulus identification/classification, and S-R mapping), varied over training sessions as RT diminished. All the priming effects either were not reduced or reduced approximately linearly at rates much slower than those predicted by the shapes of the coresponding RT learning curves. The overall results suggest that short term sequential priming and long-term practice modulate RT through relatively separate mechanisms, even though they appear to affect a common set of behaviorally defined processing stages.     

The effects of vicarious experience and stimulus intensity on pain termination and work avoidance

The purpose of the present investigation was to evaluate the role of vicarious experience in the acquisition of pain termination and work avoidance. Fifty-six experimental subjects were randomly assigned to view a film of a model who either terminated exposure to a pain stimulus and work task after 10 sec (high-avoidant) or 70 sec (low-avoidant). Following the film presentation, subjects were exposed to the pain stimulus and work task. Half of the subjects were randomly chosen to perform the task with a low-intensity pain stimulus (LP) and the other half performed the task while exposed to a high-intensity pain stimulus (HP). The results indicated that subjects in the high-avoidant model conditions (HA) did significantly less work and tolerated the pain stimulus for significantly fewer seconds compared to the low-avoidant model groups (LA). Subjects in the LP groups tolerated the pain stimulus significantly longer and did significantly more work compared to subjects in the HP groups. No significant interaction was observed. The results provide support for the hypothesis that behavioral reactions to pain can be acquired by vicarious experience. Implications for future research are discussed.     

The role of instructions,practice, and stimulus-hand correspondence on the Simon effect

Numerous studies of two-choice reaction tasks, including auditory and visual Simon tasks (i.e., tasks in which stimulus location is irrelevant) and visual compatibility tasks, have found that only spatial stimulus-response (S-R) correspondence affected S-R compatibility. Their results provided no indication that stimulus-hand correspondence was a significant factor. However, Wascher et al. (2001) suggested that hand coding plays a role in visual and auditory Simon tasks when the instructions are in terms of the finger/hand used for responding. The present experiments examined whether instructing subjects in terms of response locations or fingers/hands influenced the Simon effect for visual and auditory tasks. In Experiments 1-3, only spatial S-R correspondence contributed significantly to the Simon effect, even when the instructions were in terms of the fingers/hands. However, in Experiment 4, which used auditory stimuli and finger/hand instructions, the contribution of stimulus-hand correspondence increased with practice.     

The effect of deprivation level during noncontingent pairings and instrumental learning on subsequent instrumental performance

In Experiment 1, rats received either response-noncontingent pairings of a tone stimulus with food or response-contingent instrumental training during which only responses in the presence of the tone were reinforced. During this training rats were maintained at either 70 or 90% of their growth-adjusted predeprivation body weights. In a subsequent test phase, one-half of the subjects in each training condition were tested under either 70 or 90% body weight. Subjects which had received response-contingent instrumental training under 70% body weight responded significantly faster to presentations of the tone than did 90% body weight-trained subjects, regardless of test deprivation condition. There was no effect of the deprivation level in effect during response-noncontingent pairings. In Experiment 2, rats received noncontingent tone-reward pairings or nonpairings under either 70 or 90% body weight. In a later test phase under 90% body weight, instrumental responding to the tone was significantly faster for subjects which had received the tone-reward pairings. Deprivation level during the pairings again produced no effect. These results support two conclusions. First, the expectancy learning process appears to be relatively independent of deprivation conditions in effect when such learning takes place; and secondly, deprivation conditions in effect during instrumental learning affect the strength of S-R associative bonds formed.     

Visual priming effects as a measure of short-term visual memory

On each trial, subjects classified one of four letters as belonging to one of two categories. Visual priming occurs when the classification response is faster to a stimulus visually identical to a previous stimulus than to one identical only in name. Earlier experiments found no visual priming effects between stimuli separated by a stimulus of the same task but from the opposite classification category. Two of the five conditions in the present experiment varied the stimulus-response (S-R) contingencies in such a way that the penultimate but not the immediately preceding trial had the same contingencies. Only these two conditions gave evidence of the above type of visual priming. Visual priming was found, however, in almost all conditions when the intervening stimulus was from the same task and the same classification category. It is argued that a similarity of S-R contingency, and not simply stimulus similarity, is an important component of the visual priming effect.     

Spatial S-R compatibility with orthogonal stimulus-response relationship

Spatial stimulus-response (S-R) compatibility with unimanual two-finger choice reactions was investigated under conditions in which the spatial orientation of response keys was either parallel to or perpendicular to the orientation of the stimuli. Subjects responded to green or red lights in the left or right visual field (irrelevant stimulus location). The response keys were oriented horizontally on the left or right side of the body midline parallel to the stimuli, and were pressed with the palms facing down (Condition A), or were oriented orthogonally to the stimuli in the midsaggital plane, either horizontally and pressed with palms facing down (B) or facing up (C), or vertically and pressed with palms facing the body (D). The results for Condition A demonstrate the usual spatial S-R compatibility effect between field of stimulation and spatial position of responding finger. For Conditions B and D, a strong reaction time advantage still obtained for those stimulus-finger pairings that are compatible under Condition A. Condition C revealed an RT advantage for the opposite pairings. This shift of the compatibility effect from Condition B to Condition C indicates that the left/right distinction of fingers does not follow a simple, fixed spatio-anatomical mapping rule. The results are discussed within the framework of a hierarchical model of spatial S-R compatibility, with spatial coding and spatio-anatomical mapping as factors.     

Between-task transfer of learning from spatial compatibility to a color stroop task

Responses to a relevant stimulus dimension are faster and more accurate when the stimulus and response spatially correspond compared to when they do not, even though stimulus position is irrelevant (Simon effect). It has been demonstrated that practicing with an incompatible spatial stimulus-response (S-R) mapping before performing a Simon task can eliminate this effect. In the present study we assessed whether a learned spatially incompatible S-R mapping can be transferred to a nonspatial conflict task, hence supporting the view that transfer effects are due to acquisition of a general "respond to the opposite stimulus value" rule. To this aim, we ran two experiments in which participants performed a spatial compatibility task with either a compatible or an incompatible mapping and then transferred, after a 5 min delay, to a color Stroop task. In Experiment 1, responses were executed by pressing one of two keys on the keyboard in both practice and transfer tasks. In Experiment 2, responses were manual in the practice task and vocal in the transfer task. The spatially incompatible practice significantly reduced the color Stroop effect only when responses were manual in both tasks. These results suggest that during practice participants develop a response-selection strategy of emitting the alternative spatial response.