Shift In Response Bias Research Articles

Psychometric curves reveal changes in bias, lapse rate, and guess rate in an online vigilance task.

When human monitors are required to detect infrequent signals among noise, they typically exhibit a decline in correct detections over time. Researchers have attributed this vigilance decrement to three alternative mechanisms: shifts in response bias, losses of sensitivity, and attentional lapses. The current study examined the extent to which changes in these mechanisms contributed to the vigilance decrement in an online monitoring task. Participants in two experiments (N = 102, N = 192) completed an online signal detection task, judging whether the separation between two probes each trial exceeded a criterion value. Separation was varied across trials and data were fit with logistic psychometric curves using Bayesian hierarchical parameter estimation. Parameters representing sensitivity, response bias, attentional lapse rate, and guess rate were compared across the first and last 4 minutes of the vigil. Data gave decisive evidence of conservative bias shifts, an increased attentional lapse rate, and a decreased positive guess rate over time on task, but no strong evidence for or against an effect of sensitivity. Sensitivity decrements appear less robust than criterion shifts or attention lapses as causes of the vigilance loss.

Go-stimuli probability influences response bias in the sustained attention to response task: a signal detection theory perspective.

The sustained attention to response task (SART) is a popular measure in the psychology and neuroscience of attention. The underlying psychological cause for errors, in particular errors of commission, in the SART is actively disputed. Some researchers have suggested task-disengagement due to mind-wandering or mindlessness, and others have proposed strategic choices. In this study we explored an alternative perspective based on Signal Detection Theory, in which the high rate of commission errors in the SART reflects simply a shift in response bias (criterion) due to the high prevalence of Go-stimuli. We randomly assigned 406 participants to one of ten Go-stimuli prevalence rates (50%, 64%, 74%, 78%, 82%, 86%, 90%, 94%, 98% and 100%). As Go-stimuli prevalence increased reaction times to both Go and No-Go stimuli decreased, omission errors decreased and commission errors increased. These all were predicted from a hypothesized bias shift, but the findings were not compatible with some alternative theories of SART performance. These findings may have implications for similar tasks.

Auditory cortex reflects goal-directed movement but is not necessary for behavioral adaptation in sound-cued reward tracking.

Mounting evidence suggests that the role of sensory cortices in perceptual decision making goes beyond the mere representation of the discriminative stimuli and additionally involves the representation of nonsensory variables such as reward expectation. However, the relevance of these representations for behavior is not clear. To address this issue, we trained rats to discriminate sounds in a single-interval forced-choice task and then confronted the animals with unsignaled blockwise changes of reward probabilities. We found that unequal reward probabilities for the two choice options led to substantial shifts in response bias without concomitant reduction in stimulus discrimination. Although decisional biases were on average less extreme than required to maximize overall reinforcement, a model-based analysis revealed that rats managed to harvest >97% of rewards. Neurons in auditory cortex recorded during task performance weakly differentiated the discriminative stimuli but more strongly the subsequent goal-directed movement. Although 10-20% of units exhibited significantly different firing rates between task epochs with different response biases, control experiments showed this to result from inflated false positive rates due to unspecific temporal correlations of spiking activity rather than changing reinforcement contingencies. Transient pharmacological inactivation of auditory cortex reduced sound discriminability without affecting other measures of performance, whereas inactivation of medial prefrontal cortex affected both discriminability and bias. Together, these results suggest that auditory cortex activity only weakly reflects decisional variables during flexible updating of stimulus-response-outcome contingencies and does not play a crucial role in sound-cued adaptive behavior, beyond the representation of the discriminative stimuli.NEW & NOTEWORTHY Recent evidence suggests that sensory cortex represents nonsensory variables such as reward expectation, but the relevance of these representations for behavior is not well understood. We show that rat auditory cortex (AC) is modulated during movement and reward anticipation in a sound-cued reward tracking task, whereas AC inactivation only impaired discrimination without affecting reward tracking, consistent with a predominantly sensory role of AC.

Individual Alpha Frequency Predicts Perceived Visuotactile Simultaneity.

Temporal encoding is a key feature in multisensory processing that leads to the integration versus segregation of perceived events over time. Whether or not two events presented at different offsets are perceived as simultaneous varies widely across the general population. Such tolerance to temporal delays is known as the temporal binding window (TBW). It has been recently suggested that individual oscillatory alpha frequency (IAF) peak may represent the electrophysiological correlate of TBW, with IAF also showing a wide variability in the general population (8-12 Hz). In our work, we directly tested this hypothesis by measuring each individual's TBW during a visuotactile simultaneity judgment task while concurrently recording their electrophysiological activity. We found that the individual's TBW significantly correlated with their left parietal IAF, such that faster IAF accounted for narrower TBW. Furthermore, we found that higher prestimulus alpha power measured over the same left parietal regions accounted for more veridical responses of non-simultaneity, which may be explained either by accuracy in perceptual simultaneity or, alternatively, in line with recent proposals by a shift in response bias from more conservative (high alpha power) to more liberal (low alpha power). We propose that the length of an alpha cycle constrains the temporal resolution within which perceptual processes take place.

Does Perceived Harm Underlie Effects of Vehicle Size on Overtaking Judgments during Driving?

Previous research found that participants accepted more gaps during overtaking (in a driving simulator) when the oncoming vehicle was a motorcycle compared with larger vehicles (Levulis, DeLucia & Jupe, 2015). Results were due to the size of the vehicle independently of the type of the vehicle, and represented shifts in response bias instead of sensitivity. The implication is that drivers may perceive motorcycles as being farther away or travelling more slowly than larger vehicles due to their relatively small sizes, contributing to crashes that result from right-of-way violations (Hurt, Ouellet, & Thom, 1981; Pai, 2011). However, in Levulis et al. (2015) vehicle size was correlated with the perceived threat of collision and associated harm posed by the oncoming vehicle (collision with larger vehicles is more harmful than with smaller vehicles). To eliminate this confound, a driving simulator was used to examine whether overtaking judgments are influenced by the size of an oncoming vehicle even when threat of (simulated) collision is removed. The size-arrival effect occurred nevertheless, suggesting that participants relied on perceived distance and speed rather than perceived harm. Countermeasures to misjudgments of gaps during overtaking should include driver-assistance technologies and driver education.

An investigation of the effect of texting on hazard perception using fuzzy signal detection theory (fSDT)

Hazard perception is a multi-faceted process that requires drivers to maintain awareness of a complex driving environment. Most research studies, however, utilize behavioral responses to a small number of discrete hazardous events (e.g., response to a braking lead vehicle, vehicle lane deviations, or pedestrians) to assess a driver’s hazard perception ability. The purpose of this study was to explore how performing a texting task impacts a driver’s hazard perception ability while viewing real-world driving scenes using fSDT metrics. The results showed that texting increased perceived mental workload and reduced the participants’ ability to discriminate hazards and reduced their likelihood of responding to a hazard. The results highlight changes in the hazard perception process, suggesting that distraction causes both a loss in sensitivity and a shift in response bias. Additionally, the results indicate that these shifts are at least in part, moderated by changes in cognitive load due to the secondary task and the current driving environment. These results also highlight the complexity in which distraction can impact both the allocation of cognitive resources as well as attentional selection.

Cross-modal cueing effects of visuospatial attention on conscious somatosensory perception

ObjectiveThe impact of visuospatial attention on perception with supraliminal stimuli and stimuli at the threshold of conscious perception has been previously investigated. In this study, we assess the cross-modal effects of visuospatial attention on conscious perception for near-threshold somatosensory stimuli applied to the face. MethodsFifteen healthy participants completed two sessions of a near-threshold cross-modality cue-target discrimination/conscious detection paradigm. Each trial began with an endogenous visuospatial cue that predicted the location of a weak near-threshold electrical pulse delivered to the right or left cheek with high probability (∼75%). Participants then completed two tasks: first, a forced-choice somatosensory discrimination task (felt once or twice?) and then, a somatosensory conscious detection task (did you feel the stimulus and, if yes, where (left/right)?). Somatosensory discrimination was evaluated with the response reaction times of correctly detected targets, whereas the somatosensory conscious detection was quantified using perceptual sensitivity (d′) and response bias (beta). A 2 × 2 repeated measures ANOVA was used for statistical analysis. ResultsIn the somatosensory discrimination task (1st task), participants were significantly faster in responding to correctly detected targets (p < 0.001). In the somatosensory conscious detection task (2nd task), a significant effect of visuospatial attention on response bias (p = 0.008) was observed, suggesting that participants had a less strict criterion for stimuli preceded by spatially valid than invalid visuospatial cues. ConclusionsWe showed that spatial attention has the potential to modulate the discrimination and the conscious detection of near-threshold somatosensory stimuli as measured, respectively, by a reduction of reaction times and a shift in response bias toward less conservative responses when the cue predicted stimulus location. A shift in response bias indicates possible effects of spatial attention on internal decision processes. The lack of significant results in perceptual sensitivity (d′) could be due to weaker effects of endogenous attention on perception.

Examining a shift in response bias through two lenses: A concurrent examination of process and informational characteristics

Examining a shift in response bias through two lenses: A concurrent examination of process and informational characteristics

The Effect of Backloading Instructions on Eyewitness Identification from Simultaneous and Sequential Lineups

SummaryThe sequential lineup is multifaceted, including serial presentation of faces, multiple decisions, and often backloading (indicating to an eyewitness that a lineup contains more photos than there actually are). We evaluated the effect of backloading instructions on response bias and sensitivity with an eyewitness identification paradigm. Importantly, we included an ‘undisclosed’ condition that provided no information to participants about the number of lineup members to expect. Experiment 1 (N = 780) tested sequential lineups; Experiment 2 (N = 532) tested simultaneous lineups. As predicted, signal detection analysis showed that backloading induced participants to be more conservative in choosing from both lineup types, but did not affect d′. We conclude that the criminal justice system should be mindful of this shift in response bias, as it has implications for both guilty and innocent suspect identifications. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Not sensitive, yet less biased: A signal detection theory perspective on mindfulness, attention, and recognition memory.

The practice of mindfulness has been argued to increase attention control and improve memory performance. However, it was recently suggested that the effect of mindfulness on memory may be due to a shift in response-bias, rather than to an increase in memory-sensitivity. The present study examined the mindfulness-attention-memory triad. Participants filled in the five-facets of mindfulness questionnaire, and completed two recognition blocks; in the first attention was full, whereas in the second attention was divided during the encoding of information. It was found that the facet of non-judging (NJ) moderated the impact of attention on memory, such that responses of high NJ participants were less biased and remained constant even when attention was divided. Facets of mindfulness were not associated with memory sensitivity. These findings suggest that mindfulness may affect memory through decision making processes, rather than through directing attentional resources to the encoding of information.

Putting bias into context: The role of familiarity in identification.

Previous demonstrations of context effects in the forensic comparison sciences have shown that the number of "match" responses a person makes can be swayed by case information. Less clear is whether these effects are a result of changes in accuracy (e.g., discrimination ability), a shift in response bias (e.g., tendency to say "match" or "no match") or a mix of the 2. We present a series of experiments where we use a signal detection framework to examine the effects of case information (separately) on forensic comparison accuracy and response bias. We also explore the role of familiarity as 1 potential mechanism for case information to sway accuracy. In Experiment 1, case information about crimes perceived to be more severe swayed people to say "match" more, but had little bearing on their ability to discriminate matching and nonmatching fingerprint pairs. In Experiment 2, case information did affect accuracy when it was familiar (i.e., if a previous similar case was associated with a "match" then people were more likely to also rate the current case as a "match," even though it was not). Even when we blinded people to all extrinsic case information in Experiment 3, accuracy was significantly affected by the familiarity of the fingerprints. These results demonstrate that contextual factors can have different (and independent) influences on accuracy and response bias and that even subtle information can affect accuracy if it is sufficiently similar to the case or trace at hand.

A critical examination of the evidence for sensitivity loss in modern vigilance tasks.

It is well known that when human observers must monitor for rare but critical events, probability of detection tends to wane over time, a phenomenon known as the "vigilance decrement." Over 60 years of empirical study on this topic has culminated in the general consensus that performance suffers due to a loss in observers' ability to distinguish signal from noise (a loss in sensitivity) provided that the task loads memory and stimuli are presented at a relatively high rate. We challenge this assertion on 2 fronts: First, we contend on a theoretical level that the metrics employed to measure observer sensitivity in modern vigilance tasks (derived from signal detection theory) are inappropriate and largely uninterpretable. This contention is supported by an evaluation of recent empirical work in the vigilance domain. Second, we present the results of an experiment that demonstrates that shifts in response bias (the observer's "willingness to respond") over time can masquerade as a loss in sensitivity. Consequently, the basic underlying cause of the vigilance decrement is actually unclear, and may simply reflect a shift in response criterion rather than sensitivity. The theoretical, as well as practical implications of these conclusions are discussed with respect to sustained attention in general, and vigilance in particular.

The verbal facilitation effect: re-reading person descriptions as a system variable to improve identification performance

ABSTRACTWhen witnesses report a crime, police usually ask for a description of the perpetrator. Several studies suggested that verbalising faces leads to a detriment in identification performance (verbal overshadowing effect [VOE]) but the effect has been difficult to replicate. Here, we sought to reverse the VOE by inducing context reinstatement as a system variable through re-reading one's own description before an identification task. Participants (N = 208) watched a video film and were then dismissed (control group), only described the perpetrator, or described and later re-read their own descriptions before identification in either target-present or target-absent lineups after a 2-day or a 5-week delay. Identification accuracy was significantly higher after re-reading (85.0%) than in the no description control group (62.5%) irrespective of target presence. Data were internally replicated using a second target and corroborated by several small meta-analyses. Identification accuracy was related to description quality. Moreover, there was a tendency towards a verbal facilitation effect (VFE) rather than a VOE. Receiver operating characteristic (ROC) curve analyses confirm that our findings are not due to a shift in response bias but truly reflect improvement of recognition performance. Differences in the ecological validity of study paradigms are discussed.

Effects of oncoming vehicle size on overtaking judgments

During overtaking maneuvers on two-way highways drivers must temporarily cross into the opposite lane of traffic, and may face oncoming vehicles. To judge when it is safe to overtake, drivers must estimate the time-to-contact (TTC) of the oncoming vehicle. Information about an oncoming vehicle’s TTC is available in the optical expansion pattern, but it is below threshold during high-speed overtaking maneuvers, which require a large passing distance. Consequently, we hypothesized that drivers would rely on perceived distance and velocity, and that their overtaking judgments would be influenced by oncoming vehicle size. A driving simulator was used to examine whether overtaking judgments are influenced by the size of an oncoming vehicle, and by whether a driver actively conducts the overtaking maneuver or passively judges whether it is safe to overtake. Oncoming motorcycles resulted in more accepted gaps and false alarms than larger cars or trucks. Results were due to vehicle size independently of vehicle type, and reflected shifts in response bias rather than sensitivity. Drivers may misjudge the distances of motorcycles due to their relatively small sizes, contributing to accidents due to right-of-way violations. Results have implications for traffic safety and the potential role of driver-assistance technologies.

Alleviating the concerns with the SDT approach to reasoning: reply to Singmann and Kellen (2014).

Alleviating the concerns with the SDT approach to reasoning: reply to Singmann and Kellen (2014).

Effects of Oncoming Vehicle Size on Overtaking Judgments

In 2011, 89,000 accidents in the United States involved a vehicle passing another vehicle, which resulted in 740 deaths and 19,000 injuries (NHTSA, 2011). When passing a vehicle on a two-way highway (overtaking), a driver often must temporarily cross into the opposite lane of traffic, and may face oncoming vehicles. To avoid a collision with an oncoming vehicle, the overtaking driver must estimate the time remaining until a collision would occur with the vehicle. Although information about an oncoming vehicle’s time-to-collision is theoretically available in the optical invariant tau (Lee, 1976), it is below threshold during high-speed overtaking maneuvers, which require a large passing distance. Under such conditions, we expect drivers to rely on the oncoming vehicle’s apparent distance and velocity, and thus depth cues such as relative size. We used a driving simulator to determine whether overtaking judgments are influenced by an oncoming vehicle’s size, and on whether such judgments differ between active driving and passive viewing. Twenty-four participants viewed computer-generated scenes in which they were following a lead vehicle on a straight, two-lane, two-way highway. At the start of each scene an oncoming vehicle (motorcycle, car, delivery truck) was visible in the opposite lane. Seven seconds after the scene an auditory tone signaled participants to make an overtaking decision. Participants in the active condition passed the lead vehicle if they thought it was safe to do so. Participants in the passive condition indicated whether it was safe to pass by pressing buttons on the steering wheel. We manipulated the participant’s (and lead vehicle’s) speed (48.28 km/h, 64.37 km/h, 80.47 km/h) and the oncoming vehicle’s speed (72.42 km/h, 88.51 km/h, 104.61 km/h) and distance when the tone occurred (457.20 m, 609.60 m). This resulted in 9 safe and 9 unsafe temporal gaps based on an equation generated from analyses of actual overtaking performance (Gordon &amp; Mast, 1970). Results indicated more accepted gaps and more false alarms (accepted gap when unsafe) in front of motorcycles than larger cars or trucks. The judgments made by participants in the active and passive conditions did not differ. Analyses of signal detection theory measures of sensitivity (d-prime) and response bias (beta) suggested that the effect of vehicle size was due to shifts in response bias rather than sensitivity. Results have implications for traffic safety and for the potential role of driver-assistance technologies.

The impact of multiple show-ups on eyewitness decision-making and innocence risk.

If an eyewitness rejects a show-up, police may respond by finding a new suspect and conducting a second show-up with the same eyewitness. Police may continue finding suspects and conducting show-ups until the eyewitness makes an identification (Study 1). Relatively low criterion-setting eyewitnesses filter themselves out of the multiple show-ups procedure by choosing the first suspect with whom they are presented (Studies 2 and 3). Accordingly, response bias was more stringent on the second show-up when compared with the first, but became no more stringent with additional show-ups. Despite this stringent shift in response bias, innocence risk increased with additional show-ups, as false alarms cumulate (Studies 2 and 3). Although unbiased show-up instructions decreased innocent suspect identifications, the numbers were still discouraging (Study 4). Given the high number of innocent suspects who would be mistakenly identified through the use of multiple show-up procedures, using such identifications as evidence of guilt is questionable. Although evidence of guilt is limited to identifications from a single show-up, practical constraints might sometimes require police to use additional show-ups. Accordingly, we propose a stronger partition between evidentiary and investigative procedures.

The effect of psychological stress and expectation on auditory perception: A signal detection analysis.

Both psychological stress and predictive signals relating to expected sensory input are believed to influence perception, an influence which, when disrupted, may contribute to the generation of auditory hallucinations. The effect of stress and semantic expectation on auditory perception was therefore examined in healthy participants using an auditory signal detection task requiring the detection of speech from within white noise. Trait anxiety was found to predict the extent to which stress influenced response bias, resulting in more anxious participants adopting a more liberal criterion, and therefore experiencing more false positives, when under stress. While semantic expectation was found to increase sensitivity, its presence also generated a shift in response bias towards reporting a signal, suggesting that the erroneous perception of speech became more likely. These findings provide a potential cognitive mechanism that may explain the impact of stress on hallucination-proneness, by suggesting that stress has the tendency to alter response bias in highly anxious individuals. These results also provide support for the idea that top-down processes such as those relating to semantic expectation may contribute to the generation of auditory hallucinations.

Perceptual and decisional attenuation of tactile perception during the preparation of self- versus externally-generated movements

We investigated tactile perception during the execution of self- versus externally-generated movements. In a first experiment, we established the temporal characteristics of the movements of interest. In a second experiment, participants had to try to detect a short gap in an otherwise continuous vibratory stimulus delivered to their right wrist under conditions of rest, throwing (i.e., self-initiated movement), or catching a basketball (i.e., externally-generated movement). Our hypothesis was that different patterns of tactile sensitivity (d') and response bias (criteria c and c') would be observed as a function of the timing of gap delivery (i.e., during movement preparation or movement execution) and the type of movement (self- or externally-generated). A third experiment investigated tactile perception at rest while participants adopted different hand postures. This experiment also tested the simple preparation of the self-/externally-generated movements versus the observation of these targeted movements as performed by the experimenter. Due to sensory suppression, participants were significantly less sensitive in detecting the gap in tactile stimulation while executing the movement. Preparing to catch the ball only triggered a shift in response bias (i.e., participants were more liberal/conservative when reporting the gap in stimulation), but no change in perceptual sensitivity was observed, as compared to rest. Preparing to make a ball-throwing movement resulted in a significant decrement in tactile sensitivity, as well as a shift in participants' criterion toward their being more conservative, when responding to the presence of the target. Similar decrements were observed for the observation of self-initiated movement preparation, but not for the observation of their externally-generated counterparts. Taken together, these results demonstrate that different forms of attenuation influence tactile perception, depending on the type of movement that is executed: perceptual and decisional attenuation for self-initiated movements, but only decisional attenuation for externally-generated movements. These results suggest that the movement preparation sensorimotor contingencies are already modulated in prefrontal decision-related cortical brain areas.

Interplay of the production and picture superiority effects: A signal detection analysis

Three experiments explored the interaction between the production effect (greater memory for produced compared to non-produced study items) and the picture superiority effect (greater memory for pictures compared to words). Pictures and words were presented in a blocked (E1) or mixed (E2, E3) design, each accompanied by an instruction to silently name (non-produced condition) or quietly mouth (produced condition) the corresponding referent. Memory was then tested for all study items as well as an equal number of foil items using a speeded (E1, E2) or self-paced (E3) yes-no recognition task. Experiments 1, 2, and 3 all revealed a small but reliable production×stimulus interaction. Production was also found to result in a liberal shift in response bias that could result in the overestimation of the production effect when measured using hits instead of sensitivity. Together our findings suggest that the application of multiple distinctive processes at study produces an especially discriminative memory trace at test, more so than the summation of each process individually.