Dissociable effects of auditory attention switching and stimulus–response compatibility

Using a task-switching variant of dichotic listening, we examined the ability to intentionally switch auditory attention between two speakers. We specifically focused on possible interactions with stimulus–response compatibility. In each trial, two words, one spoken by a male and another by a female, were presented dichotically via headphones. In one experimental group, two animal names were presented, and the relevant animal had to be judged as smaller or larger than a sheep by pressing a left or right response key. In another group, two number words were presented and had to be judged as smaller or larger than 5. In each trial, a visual cue indicated the gender of the relevant speaker. Performance was worse when the gender of the relevant speaker switched from trial to trial. These switch costs were larger for animal names than for number words, suggesting stronger interference with slower access to semantic categories. Responses were slower if the side of the target stimulus (as defined by the relevant gender) was spatially incompatible with the required response (as defined by the size judgment). This stimulus–response compatibility effect did not differ across stimulus material and did not interact with attentional switch costs. These results indicate that auditory switch costs and stimulus–response compatibility effects are dissociable, referring to target selection and response selection, respectively.     

Effects of visual cue and response assignment on spatial stimulus coding in stimulus–response compatibility

Tlauka and McKenna (2000 Tlauka, M. and McKenna, F. P. 2000. Hierarchical knowledge influences stimulus–response compatibility effects. Quarterly Journal of Experimental Psychology, 53A: 85–103.  [Google Scholar]) reported a reversal of the traditional stimulus–response compatibility (SRC) effect (faster responding to a stimulus presented on the same side than to one on the opposite side) when the stimulus appearing on one side of a display is a member of a superordinate unit that is largely on the opposite side. We investigated the effects of a visual cue that explicitly shows a superordinate unit, and of assignment of multiple stimuli within each superordinate unit to one response, on the SRC effect based on superordinate unit position. Three experiments revealed that stimulus–response assignment is critical, while the visual cue plays a minor role, in eliciting the SRC effect based on the superordinate unit position. Findings suggest bidirectional interaction between perception and action and simultaneous spatial stimulus coding according to multiple frames of reference, with contribution of each coding to the SRC effect flexibly varying with task situations.     

Does sensitivity in binary choice tasks depend on response modality?

In most models of vision, a stimulus is processed in a series of dedicated visual areas, leading to categorization of this stimulus, and possible decision, which subsequently may be mapped onto a motor-response. In these models, stimulus processing is thought to be independent of the response modality. However, in theories of event coding, common coding, and sensorimotor contingency, stimuli may be very specifically mapped onto certain motor-responses. Here, we compared performance in a shape localization task and used three different response modalities: manual, saccadic, and verbal. Meta-contrast masking was employed at various inter-stimulus intervals (ISI) to manipulate target visibility. Although we found major differences in reaction times for the three response modalities, accuracy remained at the same level for each response modality (and all ISIs). Our results support the view that stimulus-response (S-R) associations exist only for specific instances, such as reflexes or skills, but not for arbitrary S-R pairings.     

Reaction time measures in deception research: Comparing the effects of irrelevant and relevant stimulus–response compatibility

Evidence regarding the validity of reaction time (RT) measures in deception research is mixed. One possible reason for this inconsistency is that structurally different RT paradigms have been used. The aim of this study was to experimentally investigate whether structural differences between RT tasks are related to how effective those tasks are for capturing deception. We achieved this aim by comparing the effectiveness of relevant and irrelevant stimulus–response compatibility (SRC) tasks. We also investigated whether an intended but not yet completed mock crime could be assessed with both tasks. Results showed (1) a larger compatibility effect in the relevant SRC task compared to the irrelevant SRC task, (2) for both the completed and the intended crime. These results were replicated in a second experiment in which a semantic feature (instead of color) was used as critical response feature in the irrelevant SRC task. The findings support the idea that a structural analysis of deception tasks helps to identify RT measures that produce robust group effects, and that strong compatibility effects for both enacted crimes as well as merely intended crimes can be found with RT measures that are based on the manipulation of relevant SRC.     

Phase-oscillator computations as neural models of stimulus–response conditioning and response selection

The activity of collections of synchronizing neurons can be represented by weakly coupled nonlinear phase oscillators satisfying Kuramoto’s equations. In this article, we build such neural-oscillator models, partly based on neurophysiological evidence, to represent approximately the learning behavior predicted and confirmed in three experiments by well-known stochastic learning models of behavioral stimulus–response theory. We use three Kuramoto oscillators to model a continuum of responses, and we provide detailed numerical simulations and analysis of the three-oscillator Kuramoto problem, including an analysis of the stability points for different coupling conditions. We show that the oscillator simulation data are well-matched to the behavioral data of the three experiments.     

The influence of the response–stimulus interval on implicit and explicit learning of stimulus sequence

Three experiments investigated the influence of the response-stimulus interval (RSI) on implicit and explicit learning of stimulus sequences. Participants responded to numerals presented in predetermined positions with alternating long and short RSIs. Half of the participants were instructed explicitly to learn the position sequence. In the transfer phase of Experiments 1 and 2, changing RSI patterns reduced the expression of incidental and intentional learning of position sequence. In Experiment 3 the position sequence was transformed, except that sub-sequences demarcated by long RSIs remained unchanged; this greatly reduced the expression of intentional learning, and slightly reduced that of incidental learning. These results indicate that in implicit learning, stimulus sequences are learned under the constraints of RSIs, whereas in explicit learning, learning independent of RSIs, as well as learning constrained by RSIs, occurs.     

Attentional control of the creation and retrieval of stimulus–response bindings

Two experiments studied the degree to which the creation and retrieval of episodic feature bindings is modulated by attentional control. Experiment 1 showed that the impact of bindings between stimulus and response features varies as a function of the current attentional set: only bindings involving stimulus features that match the current set affect behavior. Experiment 2 varied the time point at which new attentional sets were implemented—either before or after the processing of the to-be-integrated stimuli and responses. The time point did not matter, suggesting that the attentional set has no impact on feature integration proper but controls which features get access to and can thus trigger the retrieval of bindings.     

Effects of face and inanimate-object contexts on stimulus–response compatibility

Prior studies have shown that a left–right spatial compatibility effect occurs for vertically oriented stimuli relative to a background context of a face rotated 90° clockwise or counterclockwise from upright. For stimuli presented at the location of the eyes, the mapping of the right eye to a right response and the left eye to a left response, as would be viewed by the participant, yields better performance than does the opposite mapping. An issue of current interest in social cognition is whether animate objects are processed differently from inanimate ones. We investigated this issue in two experiments in which we compared the compatibility effects obtained with inanimate objects to those obtained with animate, face stimuli. The results showed left–right compatibility effects from the participant’s perspective for vehicles and faces from frontal and profile views, as well as for a road sign. Our findings indicate that coding of stimulus location relative to an external frame of reference is not restricted to face backgrounds.     

Influences of multiple spatial stimulus and response codes on orthogonal stimulus—response compatibility

When up-down stimuli are mapped to left-right responses, an up-right/down-left mapping advantage is found that is modified by response eccentricity and hand posture. These effects can be attributed to correspondence of asymmetric stimulus and response codes formed relative to multiple reference frames. We examined the influence of stimulus-set location on these orthogonal stimulus-response compatibility (SRC) effects. In Experiment 1, the stimulus set appeared in the upper or lower display positions. A spatial code for stimulus-set location was formed, producing Simon-type response eccentricity and hand posture effects, but this code had no influence on the coding of the relevant stimuli. In Experiment 2, the stimulus set appeared in the left, center, or right positions relative to the response location, which also varied, to dissociate the effects of response location, relative to the stimulus display and body midline. The former factor influenced the orthogonal SRC effect for both unimanual switch movements and bimanual keypresses, and the latter factor influenced the effect for only unimanual switch movements. Stimulus-set location causes orthogonal Simon-type effects when varied along the stimulus dimension and provides a referent for response coding when varied along the response dimension.     

The role of task rules and stimulus–response mappings in the task switching paradigm

Switch costs occur whenever participants are asked to switch between two or more task sets. In a typical task switching experiment, participants have to switch between two task sets composed of up to four different stimuli per task set. These 2 (task sets) x 4 (stimuli) contain only 8 different stimulus-response (S-R) mappings, and the question is why participants base their task performance on task sets instead of S-R mappings. The current experiments compared task performance based on task rules with performance based on single stimulus-response mappings. Participants were led to learn eight different S-R mappings with or without fore-knowledge about two underlying task sets. Without task set information no difference between shifts and repetitions occurred, whereas introducing task sets at the beginning led to significant switch costs. Most importantly, introducing task sets in the middle of the experiment also resulted in significant switch costs. Furthermore, introducing task rules at the beginning of the experiment lead to slower RTs when simple stimuli (Experiment 1) had to be processed. This detrimental effect disappeared with more complex stimuli (Experiment 2). Results will be discussed with respect to cognitive control.     

Orthogonal stimulus–response compatibility effects emerge even when the stimulus position is task irrelevant

The above-right/below-left mapping advantage with vertical stimuli and horizontal responses is known as the orthogonal stimulus–response compatibility (SRC) effect. We investigated whether the orthogonal SRC effect emerges with irrelevant stimulus dimensions. In Experiment 1, participants responded with a right or left key press to the colour of the stimulus presented above or below the fixation. We observed an above-right/below-left advantage (orthogonal Simon effect). In Experiment 2, we manipulated the polarity in the response dimension by varying the horizontal location of the response set. The orthogonal Simon effect decreased and even reversed as the left response code became more positive. This result provides evidence for the automatic activation of the positive and negative response codes by the corresponding positive and negative stimulus codes. These findings extended the orthogonal SRC effect based on coding asymmetry to an irrelevant stimulus dimension.     

Do response modality effects support multiprocessor models of divided attention?

Some studies have suggested that dual-task interference is greatly reduced when tasks requiring very different types of responses (e.g., manual and vocal) are combined. However, in those studies, the order of stimuli varied unpredictably. In Experiments 1 and 2, variable stimulus order greatly inflated interference between two manual tasks, whereas interference between a manual and a vocal task was only slightly exacerbated. However, central interference (the psychological refractory period) persisted even with the manual/vocal combination. Selection of 2 manual responses with unknown stimulus order may require a special strategy to preclude intertask intrusion errors. Experiment 3 demonstrated that such errors could be provoked with speed stress. Together, these results reconcile response modality effects with the response selection bottleneck model for dual-task interference (once it is suitably amended).     

Effector identity and orthogonal stimulus–response compatibility in blindness to response-compatible stimuli

Perceiving a visual stimulus is hampered when the stimulus is compatible with simultaneously prepared or executed action (blindness effect). We explored the roles of the effector identity of the responding hand and of orthogonal compatibility (above-right/below-left correspondence) in the blindness effect. In Experiment 1, participants conducted bimanual key presses with vertically arranged responses while perceiving a brief presentation of rightward or leftward arrowheads. A blindness effect based on the effector identity did emerge, but only with the above-right/below-left key-hand arrangement. An orthogonal blindness effect was not found in Experiment 2 with a horizontal key-press action task and a vertical arrowhead perception task. We concluded that the anatomical identity of the responding hand was not integrated into the action plan with an orthogonally incompatible key-hand arrangement. The findings are discussed in terms of the generality and limits of the blindness effect, and hierarchical response coding.     

Subjective reports of stimulus,response, and decision times in speeded tasks: How accurate are decision time reports?

Four experiments examined how accurately participants can report the times of their own decisions. Within an auditory reaction time (RT) task, participants reported the time at which (a) the tone was presented, (b) they decided on the response, or (c) the response key was pressed. Decision time reports were checked for plausibility against the actual RTs, and we compared the effects of experimental manipulations on these two measures to see whether the reported decision times showed appropriate effects. In addition, we estimated the amount of error associated with individual decision time reports by checking how often participants’ decision time reports were implausibly early (i.e., before stimulus onset) or late (i.e., after response), and by using several quantitative models. Overall, the results suggest that decision time reports are not very accurate but they may be usable for some purposes.     

Effects of response–stimulus interval manipulation and articulatory suppression on task switching

We conducted three experiments using a list paradigm to examine how articulatory suppression and response–stimulus interval (RSI) manipulation affected task switching. Experiments 1 and 2 tested task-switching performance under a short and long RSI and three concurrent task conditions (control, articulatory suppression, and tapping) without external task cues. The results indicated that alternation had a greater effect under articulatory suppression than under the control and tapping conditions, and that articulatory suppression costs were unrelated to the RSI. In Experiment 3, an external task cue was provided with each stimulus, and the negative effect of articulatory suppression on alternation cost was eliminated. These results indicated that articulatory suppression effects did not differ between conditions of short and long RSI and that the availability of verbal representations of task information was independent of RSI length. This paper discussed the possible roles played by the phonological loop in task-switching paradigms.     

Dissecting stimulus–response binding effects: Grouping by color separately impacts integration and retrieval processes

In selection tasks, target and distractor features can be encoded together with the response into the same short-lived memory trace, or event file (see Hommel, 2004), leading to bindings between stimulus and response features. The repetition of a stored target or distractor feature can lead to the retrieval of the entire episode, including the response—so-called “binding effects.” Binding effects due to distractor repetition are stronger for grouped than for nongrouped target and distractor stimulus configurations. Modulation of either of two mechanisms that lead to the observed binding effects might be responsible here: Grouping may influence either stimulus–response integration or stimulus–response retrieval. In the present study we investigated the influences of grouping on both mechanisms independently. In two experiments, target and distractor letters were grouped (or nongrouped) via color (dis)similarity separately during integration and retrieval. Grouping by color similarity affected integration and retrieval mechanisms independently and in different ways. Color dissimilarity enhanced distractor-based retrieval, whereas color similarity enhanced distractor integration. We concluded that stimulus grouping is relevant for binding effects, but that the mechanisms that contribute to binding effects should be carefully separated.     

Influence of stimulus–response assignment on the joint-action correspondence effect

Sebanz et al. (Cognition 88:B11–B21, 2003) have shown that spatial correspondence effects are observed even when the two-choice reaction time task is distributed between two people, such that each person is assigned only one of two possible stimulus–response (S–R) pairings. The effect is similar to when one person is assigned and responds to both S–R pairings. These results have been taken to suggest that two people performing a complementary task co-represent each other’s response alternatives. In our experiment, we examined performance when paired participants responded to the same S–R alternative. We reasoned that co-representation would be of little advantage as the task alternatives would be the same for both participants. Correspondence effects were absent when paired participants responded to the same S–R alternative but emerged when they responded to different alternatives.     

Deconstructing Marilyn: Robust effects of face contexts on stimulus—response compatibility

Hommel and Lippa (1995) found a left-right spatial compatibility effect with respect to a background context of Marilyn Monroe's face, rotated 90 degrees clockwise or counterclockwise from upright, when subjects responded to up or down stimuli by pressing a left or a right key. They interpreted their results as providing evidence for object-based coding of stimulus location. We conducted four experiments in order to evaluate the reliability of this face context effect, to control for possible artifacts and evaluate alternative explanations, and to establish generalizability to other face contexts. This was accomplished by using not only the original photograph, but also a mirror-reversed image, chimeric faces composed from the left or the right sides of the original photograph, an outline drawing face, and a circle with markings for facial features. Our results were much stronger than those of Hommel and Lippa, and the face context effect was found for all of the face variations. Our experiments also provided evidence to suggest that asymmetric coding of the up and down locations contributes to performance in the face context as well.     

Effects of stimulus–stimulus short-term memory associations in a Simon-like task

The Simon effect refers to faster responding when an irrelevant stimulus location corresponds with the response to a relevant stimulus attribute than when it does not. We investigated whether a memory-based Simon-like effect would occur when the irrelevant spatial attribute was associated with the stimulus during a prior task. In a first task, an association between colour and location was formed by requiring participants to count the occurrences of two colour stimuli, each of which was always presented in a left or right location. In a second task, the colour stimuli were presented centrally and mapped to left and right keypresses, with the mapping being inconsistent or consistent with the prior colour-location associations. A Simon-like effect was evident at the start of the second task, with performance being better when the established colour–position associations were consistent with the colour–response mapping than when they were not. This result indicates that stimulus–stimulus short-term memory associations formed during the first task transferred to the second task. For the remainder of the second task, the data showed a more conservative speed–accuracy criterion for the inconsistent condition than for the consistent condition, though a processing efficiency measure suggested that the prior stimulus–stimulus short-term associations may also continue to directly influence performance. Results suggest that simple declarative knowledge, as represented by stimulus–stimulus STM links, exerts less persistent transfer effects than procedural knowledge as provided by stimulus–response STM links.     

Same-hand and different-hand finger pairings in two-choice reaction time: presence or absence of response competition?

Several two-choice reaction time experiments have compared conditions in which the two possible responses were from the same hand (same-hand pairing) or from different hands (different-hand pairing). Studies that used only the two relevant fingers on response keys reported shorter reaction times for the different-hand pairing. In other studies, two additional but irrelevant fingers were also in contact with response keys. These fingers were irrelevant in the sense that they never were required to respond. With this procedure, equivalent reaction times were found between same-hand and different-hand pairings. Reeve and Proctor (1988) recently have argued that using only two fingers results in response competition between the two fingers from the same hand, yielding shorter reaction times for the different-hand pairing condition. In contrast, when four fingers are placed on response keys, response competition should be absent for both the same-hand and the different-hand pairing conditions, resulting in equivalent reaction times. In the present work, reaction times associated with the same-hand pairing condition remained unchanged, irrespective of the number of fingers positioned on keys. In the different-hand pairing condition, reaction times were found to be longer when four fingers were used than when only two fingers rested on response keys. Thus, when four fingers are placed on keys, response competition appears to be present rather than absent. Other results showed that the response competition found in the different-hand pairing condition decreases with practice.