Keypress Responses Research Articles

Facilitation and interference of behavioral responses by task-irrelevant affect-laden stimuli

Emotional interference on behavior is commonly observed when task-irrelevant negative stimuli appear before behavioral targets. One explanation postulates that affect-laden stimuli readily capture attention, interfering with the processing of the upcoming target. Emotional stimuli might also preactivate motor programs incompatible with the demanded response. Using a cued go/no-go procedure we showed that task-irrelevant unpleasant stimuli cause interference or facilitation depending on their onset asynchrony relative to the target. We observed interference with short (200 ms) stimulus-target asynchronies and facilitation for longer ones (600 ms), both for key press (Experiment 1) and key release (Experiment 2) responses. The interference effect is compatible with an attentional explanation, but the behavioral facilitation is hard to accommodate within either attentional or motor accounts. This interference-facilitation pattern can be explained assuming that once the attentional effect subsides, emotional processing may enhance the perceptual processing of the stimuli, or lower the decision threshold, thereby facilitating the response selection process.

Psychophysics of EEG alpha state discrimination

Nearly all research in neurofeedback since the 1960s has focused on training voluntary control over EEG constructs. By contrast, EEG state discrimination training focuses on awareness of subjective correlates of EEG states. This study presents the first successful replication of EEG alpha state discrimination first reported by Kamiya (1962). A 150-s baseline was recorded in 106 participants. During the task, low (<30th percentile of the baseline) and high alpha events (>70th percentile) triggered a prompt. Participants indicated "high" or "low" with a keypress response and received immediate feedback. Seventy-five percent of participants achieved significant discrimination within nine sessions, with a significant learning curve effect. Performance was significantly related to physical properties of the EEG signal, including magnitude, duration, and absolute vs. relative amplitude. These results are consistent with a conceptualization of EEG state discrimination as a sensory modality, although it is also intricately related to voluntary control of these states.

Correlation and response relevance in sequence learning

We tested the effects of introducing a secondary sequence into the serial reaction time task. Specifically, we examined the role of correlated streams of information and response relevance. In the first experiment, the order of stimulus locations was correlated with the order of key press responses in the conventional way. A symbol-identity sequence, of a different length, was also present but no manual responses were made to it, and it was not correlated with any other stream of information. In the second experiment, two concurrent streams of location-based stimuli were presented. Both were sequenced but only one sequence required responses. Importantly, the sequences were either correlated with one another or not (same vs. different lengths). In the third experiment, the same design was used but with one sequence visual and the other auditory. In all three experiments, participants became sensitive to the sequence that required responses, and resultant knowledge was largely explicit. They were also sensitive to the sequence that did not require responses but only when it was correlated with the sequence that did, and here resultant knowledge was implicit. The findings suggest that the presence of a secondary sequence can affect learning, but only when stimuli in that sequence are integrated, through correlation, with responses made to the primary sequence.

The Function Acquisition Speed Test (FAST): A Behavior Analytic Implicit Test for Assessing Stimulus Relations

Subjects completed a baseline stimulus matching procedure designed to produce two symmetrical stimulus relations; A1–B1 and A2–B2. Using A1, B1, and two novel stimuli, subjects were then trained to produce a common keypress response for two stimuli and a second key-press response for two further stimuli across two blocks of response training. During one block, the reinforcement contingencies were consistent with baseline relations (i.e., A1 and B1 shared a response function), whereas during the other block they were not. Thirteen of 18 subjects who completed the procedure showed a response class acquisition rate differential across the two test blocks in the predicted direction. It is suggested that this procedure may serve as a behavior analytic alternative to popular implicit tests. It provides a nonrelative measure of stimulus association strength and may display superior procedural implicitness over other tests.

Do task-irrelevant direction-associated motion verbs affect action planning? Evidence from a Stroop paradigm

Does simply seeing a word such as rise activate upward responses? The present study is concerned with bottom-up activation of motion-related experiential traces. Verbs referring to an upward or downward motion (e.g., rise/fall) were presented in one of four colors. Participants had to perform an upward or downward hand movement (experiments 1 and 2a/2b) or a stationary up or down located keypress response (experiment 3) according to font color. In all experiments, responding was faster if the word's immanent motion direction matched the response (e.g., upward/up response in case of rise); however, this effect was strongest in the experiments requiring an actual upward or downward response movement (experiments 1 and 2a/2b). These findings suggest bottom-up activation of motion-related experiential traces, even if the task does not demand lexical access or focusing on a word's meaning.

Inhibitory effects on response force in the stop-signal paradigm.

The forcefulness of key press responses was measured in stop-all and selective stopping versions of the stop-signal paradigm. When stop signals were presented too late for participants to succeed in stopping their responses, response force was nonetheless reduced relative to trials in which no stop signal was presented. This effect shows that peripheral motor aspects of primary task responses can still be influenced by inhibition even when the stop signal arrives too late to prevent the response. It thus requires modification of race models in which responses in the presence of stop signals are either stopped completely or produced normally, depending on whether the responding or stopping process finishes first.

The Activation of Effect Codes in Response Preparation: New Evidence from an Indirect Priming Paradigm

Evidence for the anticipation of environmental effects as an integral part of response planning comes mainly from experiments in which the effects were physically presented. Thus, in these studies it cannot be excluded that effect codes were activated during response preparation only because the effects were displayed as external stimuli before response execution. In order to provide more clear-cut evidence for the anticipation of response effects in action planning, we performed a series of three experiments using a new paradigm, where displaying effect codes before the response was avoided. Participants first learned arbitrary effects of key-pressing responses. In the following test phase they were instructed to execute a response only if a Go stimulus was presented after a variable stimulus onset asynchrony (SOA). The Go stimulus was either compatible or incompatible with the effect, but independent of the response. In Experiment 1 we tested the paradigm with two responses and two effects. We found a significant compatibility effect: If the Go stimulus was compatible with the response effect, responses were initiated faster than in incompatible trials. In Experiment 2 response effects were only present in the acquisition phase, but not in the test phase. The compatibility effect disappeared, indicating that the results of Experiment 1 were indeed related to the anticipation of the forthcoming response effects. In Experiment 3 we extended this paradigm by using a larger number of stimuli and response alternatives. Again we found a robust compatibility effect, which can only be explained if the effect representations are active before response execution. The compatibility effects in Experiments 1 and 3 did not depend on the SOA. The fact that the Go stimulus affected response preparation at any time indicates that the role of effect anticipation is not limited to response selection.

Big Time Is Not Always Long

To reproduce the duration of an event precisely, one needs to represent the temporal information without being influenced by other magnitude attributes (e.g., size) of the event. In the present study, however, task-irrelevant numerical magnitude automatically affected participants’ reproduction of the duration of a stimulus. In Experiment 1, participants made key-press responses to reproduce the duration of numbers. Reproduced durations were shorter for small numbers (e.g., 1) than for large numbers (e.g., 9). In contrast, in Experiment 2, participants’ reproductions of a standard duration were longer when their key-press response was accompanied by visual presentation of a small number than when it was accompanied by presentation of a large number. These results clearly demonstrate that number-time interference extends beyond simple mapping between stimulus categories and response alternatives. The findings support the notion that either a common magnitude representation or closely connected magnitude representations underlie numerical and temporal processing.

Pilot attention allocation model based on fuzzy theory

Quantitative research into a pilot’s attention allocation mechanism is required in the optimization design of an aircraft human–machine interface and system evaluation. After making a comprehensive consideration of several factors, including the importance of information, information detective efficiency and human errors, a pilot attention allocation model was built on the basis of hybrid entropy. In order to make a verification of the pilot attention allocation model, a simulation model of a head-up display (HUD) used to present flight indicators was developed. After setting the membership degrees of the importance for different indicators according to their priorities, the experiments on the key-press response and eye-movement tracking were designed and carried out under the cruise and hold modes. As the experiment results are in good agreement with the theoretical model, the effectiveness of the pilot attention allocation model based on fuzzy theory is confirmed.

Inferred threat and safety: Symbolic generalization of human avoidance learning

Symbolic generalization of avoidance may underlie the aetiology and maintenance of anxiety disorders. The aim of the present study was to demonstrate inferred threat-avoidance and safety (non-avoidance) behaviours that occur in the presence of stimuli indirectly related to learned threat and safety cues. A laboratory experiment was conducted involving two symbolic stimulus equivalence relations consisting of three physically dissimilar stimuli (avoidance cues: AV1–AV2–AV3 and neutral cues: N1–N2–N3). During avoidance learning involving aversive images and sounds, a key-press avoidance response was trained for one member of one of the relations (AV2) and non-avoidance for another (N2). Inferred threat and safety behaviour and ratings of the likelihood of aversive events were tested with presentations of all remaining stimuli. Findings showed a significantly high percentage of avoidance to both the learned and inferred threat cues and less avoidance to both the learned and inferred safety cues. Ratings in the absence of avoidance were high during training and testing to threat cues and low to safety cues and were generally lower in the presence of avoidance. Implications for associative and behavioural accounts of avoidance, and modern therapies for anxiety disorders are discussed.

Effect of Visual-Verbal Load and Spatial Compatibility on Stimulus Response

This study examined the effects of visual-verbalload (as measured by a visually presented reading-memory task with three levels) on a visual/auditory stimulus-response task. The three levels of load were defined as follows: "No Load" meant no other stimuli were presented concurrently; "Free Load" meant that a letter (A, B, C, or D) appeared at the same time as the visual or auditory stimulus; and "Force Load" was the same as "Free Load," but the participants were also instructed to count how many times the letter A appeared. The stimulus-response task also had three levels: "irrelevant," "compatible," and "incompatible" spatial conditions. These required different key-pressing responses. The visual stimulus was a red ball presented either to the left or to the right of the display screen, and the auditory stimulus was a tone delivered from a position similar to that of the visual stimulus. Participants also processed an irrelevant stimulus. The results indicated that participants perceived auditory stimuli earlier than visual stimuli and reacted faster under stimulus-response compatible conditions. These results held even under a high visual-verbal load. These findings suggest the following guidelines for systems used in driving: an auditory source, appropriately compatible signal and manual-response positions, and a visually simplified background.

Response preparation with anticues in children and adults

We examined the ability of children (mean age: 10.4 years) and adults (mean age: 20.7 years) to prepare finger keypress responses in an anticue paradigm by presenting left and right spatial cues, which specified right and left hand finger responses, respectively. Four time intervals separated cue onset from target onset: 200 ms, 600 ms, 1000 ms, and 2000 ms. Results showed that, overall, children responded slower and less accurately than did adults; nevertheless they were equally effective in using anticue information to reduce reaction time with preparation intervals of 600 ms and longer. This outcome is discussed in terms of a slow, voluntary, top-down executive process that redirects motor preparation from the ipsi- to the contralateral hand. The absence of an age effect suggests an early maturation of the underlying neural mechanisms.

Correspondence effects for objects with opposing left and right protrusions.

Choice reactions to a property of an object stimulus are often faster when the location of a graspable part of the object corresponds with the location of a keypress response than when it does not, a phenomenon called the object-based Simon effect. Experiments 1-3 examined this effect for variants of teapot stimuli that were oriented to the left or right. Whether keypress responses were made with fingers within the same hand or between different hands was also manipulated. Experiment 1 showed that, for judgments of stimulus color and upright-inverted orientation, the Simon effect for intact teapots occurred in the direction of the spout location and was larger for within- than between-hand response modes. In Experiments 2 and 3, teapots with the handle or spout removed showed separate contributions of each component to the Simon effect. In Experiment 4, we clarified a discrepancy between our findings of object-based Simon effects and a previously reported absence of effect with color judgments for door-handle stimuli. We obtained an object-based Simon effect with respect to handle position when the bases of the door handles were centered but not when the handles were centered. The findings that object-based Simon effects occur with color judgments and when responses are fingers on the same hand are in closer agreement with a location coding account than with a grasping affordance account.

Visual Processing in Rapid-Chase Systems: Image Processing, Attention, and Awareness

Visual stimuli can be classified so rapidly that their analysis may be based on a single sweep of feedforward processing through the visuomotor system. Behavioral criteria for feedforward processing can be evaluated in response priming tasks where speeded pointing or keypress responses are performed toward target stimuli which are preceded by prime stimuli. We apply this method to several classes of complex stimuli. (1) When participants classify natural images into animals or non-animals, the time course of their pointing responses indicates that prime and target signals remain strictly sequential throughout all processing stages, meeting stringent behavioral criteria for feedforward processing (rapid-chase criteria). (2) Such priming effects are boosted by selective visual attention for positions, shapes, and colors, in a way consistent with bottom-up enhancement of visuomotor processing, even when primes cannot be consciously identified. (3) Speeded processing of phobic images is observed in participants specifically fearful of spiders or snakes, suggesting enhancement of feedforward processing by long-term perceptual learning. (4) When the perceived brightness of primes in complex displays is altered by means of illumination or transparency illusions, priming effects in speeded keypress responses can systematically contradict subjective brightness judgments, such that one prime appears brighter than the other but activates motor responses as if it was darker. We propose that response priming captures the output of the first feedforward pass of visual signals through the visuomotor system, and that this output lacks some characteristic features of more elaborate, recurrent processing. This way, visuomotor measures may become dissociated from several aspects of conscious vision. We argue that “fast” visuomotor measures predominantly driven by feedforward processing should supplement “slow” psychophysical measures predominantly based on visual awareness.

Prediction and uncertainty in human Pavlovian to instrumental transfer.

Attentional capture and behavioral control by conditioned stimuli have been dissociated in animals. The current study assessed this dissociation in humans. Participants were trained on a Pavlovian schedule in which 3 visual stimuli, A, B, and C, predicted the occurrence of an aversive noise with 90%, 50%, or 10% probability, respectively. Participants then went on to separate instrumental training in which a key-press response canceled the aversive noise with a .5 probability on a variable interval schedule. Finally, in the transfer phase, the 3 Pavlovian stimuli were presented in this instrumental schedule and were no longer differentially predictive of the outcome. Observing times and gaze dwell time indexed attention to these stimuli in both training and transfer. Aware participants acquired veridical outcome expectancies in training--that is, A > B > C, and these expectancies persisted into transfer. Most important, the transfer effect accorded with these expectancies, A > B > C. By contrast, observing times accorded with uncertainty--that is, they showed B > A = C during training, and B < A = C in the transfer phase. Dwell time bias supported this association between attention and uncertainty, although these data showed a slightly more complicated pattern. Overall, the study suggests that transfer is linked to outcome prediction and is dissociated from attention to conditioned stimuli, which is linked to outcome uncertainty.

Effects of Saccades and Response Type on the Simon Effect: If you Look at the Stimulus, the Simon Effect May be Gone

The Simon effect has most often been investigated with key-press responses and eye fixation. In the present study, we asked how the type of eye movement and the type of manual response affect response selection in a Simon task. We investigated three eye movement instructions (spontaneous, saccade, and fixation) while participants performed goal-directed (i.e., reaching) or symbolic (i.e., finger-lift) responses. Initially, no oculomotor constraints were imposed, and a Simon effect was present for both response types. Next, eye movements were constrained. Participants had to either make a saccade toward the stimulus or maintain gaze fixed in the screen centre. While a congruency effect was always observed in reaching responses, it disappeared in finger-lift responses. We suggest that the redirection of saccades from the stimulus to the correct response location in noncorresponding trials contributes to the Simon effect. Because of eye-hand coupling, this occurred in a mandatory manner with reaching responses but not with finger-lift responses. Thus, the Simon effect with key-presses disappears when participants do what they typically do--look at the stimulus.

Response priming driven by local contrast, not subjective brightness

We demonstrate qualitative dissociations of brightness processing in visuomotor priming and conscious vision. Speeded keypress responses to the brighter of two luminance targets were performed in the presence of preceding dark and bright primes (clearly visible and flanking the targets) whose apparent brightness values were enhanced or attenuated by a visual illusion. Response times to the targets were greatly affected by consistent versus inconsistent arrangements of the primes, relative to the targets (response priming). Priming effects could systematically contradict subjective brightness matches, such that one prime could appear brighter than the other but could prime as if it were darker. Systematic variation of the illusion showed that response-priming effects depended only on local flanker-background contrast, not on the subjective appearance of the flankers. Our findings suggest that speeded motor responses, as opposed to conscious perceptual judgments, access an early phase of lightness and brightness processing prior to full lightness constancy.

Response priming driven by local contrast, not subjective brightness

We demonstrate qualitative dissociations of brightness processing in visuomotor priming and conscious vision. Speeded keypress responses to the brighter of two luminance targets were performed in the presence of preceding dark and bright primes (clearly visible and flanking the targets) whose apparent brightness values were enhanced or attenuated by a visual illusion. Response times to the targets were greatly affected by consistent versus inconsistent arrangements of the primes, relative to the targets (response priming). Priming effects could systematically contradict subjective brightness matches, such that one prime could appear brighter than the other but could prime as if it were darker. Systematic variation of the illusion showed that response-priming effects depended only on local flanker-background contrast, not on the subjective appearance of the flankers. Our findings suggest that speeded motor responses, as opposed to conscious perceptual judgments, access an early phase of lightness and brightness processing prior to full lightness constancy.

Recurrent, robust and scalable patterns underlie human approach and avoidance.

BackgroundApproach and avoidance behavior provide a means for assessing the rewarding or aversive value of stimuli, and can be quantified by a keypress procedure whereby subjects work to increase (approach), decrease (avoid), or do nothing about time of exposure to a rewarding/aversive stimulus. To investigate whether approach/avoidance behavior might be governed by quantitative principles that meet engineering criteria for lawfulness and that encode known features of reward/aversion function, we evaluated whether keypress responses toward pictures with potential motivational value produced any regular patterns, such as a trade-off between approach and avoidance, or recurrent lawful patterns as observed with prospect theory.Methodology/Principal FindingsThree sets of experiments employed this task with beautiful face images, a standardized set of affective photographs, and pictures of food during controlled states of hunger and satiety. An iterative modeling approach to data identified multiple law-like patterns, based on variables grounded in the individual. These patterns were consistent across stimulus types, robust to noise, describable by a simple power law, and scalable between individuals and groups. Patterns included: (i) a preference trade-off counterbalancing approach and avoidance, (ii) a value function linking preference intensity to uncertainty about preference, and (iii) a saturation function linking preference intensity to its standard deviation, thereby setting limits to both.Conclusions/SignificanceThese law-like patterns were compatible with critical features of prospect theory, the matching law, and alliesthesia. Furthermore, they appeared consistent with both mean-variance and expected utility approaches to the assessment of risk. Ordering of responses across categories of stimuli demonstrated three properties thought to be relevant for preference-based choice, suggesting these patterns might be grouped together as a relative preference theory. Since variables in these patterns have been associated with reward circuitry structure and function, they may provide a method for quantitative phenotyping of normative and pathological function (e.g., psychiatric illness).

The rate of binocular rivalry -- Visual field asymmetries

At the core of the binocular rivalry phenomenon lies the spontaneous alternation between the two percepts. Understanding what drives that alternation is a major and key part of understanding the neural basis of binocular rivalry. A starting point in this direction is to characterize the factors that determine the rivalry alternation rate. It is known that some stimulus factors (e.g., contrast) can influence the rate of rivalry, here we tested whether stimuli projected to different parts of the cortex have different rivalry rates. Is there a visual field asymmetry of the rivalry dynamics? Eight near peripheral locations were tested: two eccentricity levels (1 and 4 degrees) at the four major meridians. A red circular grating and a green radius grating were dichoptically presented to the two eyes. Observers were asked to track their perceptual experience by making keypress responses to indicate which of the stimuli came into view. Results from 10 observers (two authors and eight naive observers) show that the alternation rate in binocular rivalry is faster when the stimuli were presented to the right visual field compared to when they were presented to the left visual field. Similarly, rival stimuli in the lower visual field generated faster alternations than that in the upper visual field. There are a number of potential reasons that can lead to the observed rivalry asymmetry. For example, visual attention maybe biased towards the lower and the right visual fields, or at the site of binocular rivalry, the time course of neuronal responses could be faster for information from the lower and right visual fields than that from the upper and left visual fields. In any case, this visual field dependence suggests that the process of binocular rivalry is influenced by retinotopically specific mechanisms.