Blocks Of Trials Research Articles

Emphasizing responder speed or accuracy modulates but does not abolish the distractor-induced quitting effect in visual search

When a highly salient distractor is present in a search array, it speeds target absent visual search and increases errors during target present visual search, suggesting lowered quitting thresholds (Moher in Psychol Sci 31(1):31–42, 2020). Missing a critical target in the presence of a highly salient distractor can have dire consequences in real-world search tasks where accurate target detection is crucial, such as baggage screening. As such, the current study examined whether emphasizing either accuracy or speed would eliminate the distractor-generated quitting threshold effect (QTE). Three blocks of a target detection search task which included a highly salient distractor on half of all trials were used. In one block, participants received no instructions or feedback regarding performance. In the remaining two blocks, they received instructions and trial-by-trial feedback that either emphasized response speed or response accuracy. Overall, the distractor lowered quitting thresholds, regardless of whether response speed or response accuracy was emphasized in a block of trials. However, the effect of the distractor on target misses was smaller when accuracy was emphasized. It, therefore, appears that while the distractor QTE is not easily eradicated by explicit instructions and feedback, it can be shifted. As such, future research should examine the applicability of these and similar strategies in real-world search scenarios.

Further observations on the reinforcing value of sucrose solutions: Interaction between quantity and concentration

According to the Multiplicative Hyperbolic Model of reinforcer value (MHM), the value of a reinforcer is an increasing hyperbolic function of its size. In addition it is generally accepted that in the case of soluble reinforcers such as sucrose, value is an increasing function of molar concentration. The present experiment examined the interaction between size and concentration on the effectiveness of sucrose reinforcers in an operant choice paradigm. Rats were trained under an adjusting-magnitude schedule in which a response on lever B delivered a fixed volume of a sucrose solution, while a response on lever A delivered a 0.8-M sucrose solution, the volume of which, qA, was adjusted according to the rats’ choices. When B was preferred in a given block of trials, qA was increased in the following block; when A was preferred, qA was reduced in the following block. The concentration and volume of B (cB, qB) were varied across six phases of the experiment and the corresponding indifference magnitudes of A (qA(50)) were measured. Log qA(50) increased and qB/qA(50) declined as approximately linear functions of log cB, consistent with the supposition that reinforcer value was determined by multiplicative combination of hyperbolic expressions representing concentration and volume.

Crossmodal cueing of masker location in a localization-in-noise task

Simpson et al. [JASA 129(4), 2489, (2011)] found that localization of a target presented in a simultaneous masker improved when, on a trial-by-trial basis, a preview of the masking stimulus was presented at the location of the upcoming masker. Subsequent research revealed that this improvement resulted solely from cueing the location of the masker (i.e., cueing spectro-temporal properties of the masker provided no additional benefit). In the present study, we examined the degree to which the benefit of cueing masker location depended on the modality in which this cue was provided. In separate blocks of trials, the location of the masker was cued auditorily, visually (LED activated at the masker location) and audio-visually, and compared to performance in a no-cue baseline. The results revealed a substantial (∼10 dB) benefit of cueing the masker auditorily over the no-cue condition, consistent with previous results. Importantly, there was also a substantial (albeit smaller) benefit of a visual cue (∼6 dB). Performance with a bimodal cue was no different than performance with an auditory cue. Thus, although hearing a sound from the upcoming masker location was most effective, the ability to effectively cue space crossmodally suggests that the spatial information itself is most critical.

Robust within-session modulations of IAT scores may reveal novel dynamics of rapid change

The Implicit Association Test (IAT) is employed in the domain of social psychology as a measure of implicit evaluation. Participants in this task complete blocks of trials where they are asked to respond to categories and attributes (e.g., types of faces and types of words). Reaction times in different blocks sharing certain response combinations are averaged and then subtracted from blocks with other response combinations and then normalized, the result of which is taken as a measure indicating implicit evaluation toward or away from the given categories. One assumption of this approach is stationarity of response time distributions, or at a minimum, that temporal dynamics in response times are not theoretically relevant. Here we test these assumptions, examine the extent to which response times change within the IAT blocks and, if so, how trajectories of change are meaningful in relation to external measures. Using multiple data sets we demonstrate within-session changes in IAT scores. Further, we demonstrate that dissociable components in the trajectories of IAT performance may be linked to theoretically distinct processes of cognitive biases as well as behaviors. The present work presents evidence that IAT performance changes within the task, while future work is needed to fully assess the implications of these temporal dynamics.

Mixtures of strategies underlie rodent behavior during reversal learning.

In reversal learning tasks, the behavior of humans and animals is often assumed to be uniform within single experimental sessions to facilitate data analysis and model fitting. However, behavior of agents can display substantial variability in single experimental sessions, as they execute different blocks of trials with different transition dynamics. Here, we observed that in a deterministic reversal learning task, mice display noisy and sub-optimal choice transitions even at the expert stages of learning. We investigated two sources of the sub-optimality in the behavior. First, we found that mice exhibit a high lapse rate during task execution, as they reverted to unrewarded directions after choice transitions. Second, we unexpectedly found that a majority of mice did not execute a uniform strategy, but rather mixed between several behavioral modes with different transition dynamics. We quantified the use of such mixtures with a state-space model, block Hidden Markov Model (block HMM), to dissociate the mixtures of dynamic choice transitions in individual blocks of trials. Additionally, we found that blockHMM transition modes in rodent behavior can be accounted for by two different types of behavioral algorithms, model-free or inference-based learning, that might be used to solve the task. Combining these approaches, we found that mice used a mixture of both exploratory, model-free strategies and deterministic, inference-based behavior in the task, explaining their overall noisy choice sequences. Together, our combined computational approach highlights intrinsic sources of noise in rodent reversal learning behavior and provides a richer description of behavior than conventional techniques, while uncovering the hidden states that underlie the block-by-block transitions.

Expected distractor context biases the attentional template for target shapes.

Visual search is supported by an internal representation of the target, the attentional template. However, which features are diagnostic of target presence critically depends on the distractors. Accordingly, previous research showed that consistent distractor context shapes the attentional template for simple targets, with the template emphasizing diagnostic dimensions (e.g., color or orientation) in blocks of trials. Here, we investigated how distractor expectations bias attentional templates for complex shapes, and tested whether such biases reflect intertrial priming or can be instantiated flexibly. Participants searched for novel shapes (cued by name) in two probabilistic distractor contexts: Either the target's orientation or rectilinearity was unique (80% validity). Across four experiments, performance was better when the distractor context was expected, indicating that target features in the expected diagnostic dimension were emphasized. Attentional templates were biased by distractor expectations when distractor context was blocked, also for participants reporting no awareness of the manipulation. Interestingly, attentional templates were also biased when distractor context was cued on a trial-by-trial basis, but only when the two contexts were consistently presented at distinct spatial locations. These results show that attentional templates can flexibly and adaptively incorporate expectations about target-distractor relations when looking for the same object in different contexts. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Maintaining eye fixation relieves pressure of cognitive action control

Cognitive control enables humans to behave guided by their current goals and intentions. Cognitive control in one task generally suffers when humans try to engage in another task on top. However, we discovered an additional task that supports conflict resolution. In two experiments, participants performed a spatial cognitive control task. For different blocks of trials, they either received no instruction regarding eye movements or were asked to maintain the eyes fixated on a stimulus. The additional eye fixation task did not reduce task performance, but selectively ameliorated the adverse effects of cognitive conflicts on reaction times (Experiment 1). Likewise, in urgent situations, the additional task reduced performance impairments due to stimulus-driven processing overpowering cognitive control (Experiment 2). These findings suggest that maintaining eye fixation locks attentional resources that would otherwise induce spatial cognitive conflicts. This reveals an attentional disinhibition that boosts goal-directed action by relieving pressure from cognitive control.

Cone-isolation contrast sensitivity – do pupil and stimulus sizes matter?

ABSTRACT Clinical relevance Computer-based colour perception tests permit clinical assessment of cone-specific pathways, proving valuable for both identifying type and severity of hereditary colour vision deficiency and enhanced detection and monitoring of acquired colour deficiency from disease. Understanding the parameters that affect computer-based colour perception tests may enhance their veracity and clinical utility. Background Testing contrast sensitivity separately for the three cone systems enables a quantification of colour perception that can be clinically useful. This study evaluated the effects of pupil diameter and stimulus size on cone contrast sensitivity (CCS) assessed with the ColorDx (Konan Medical, Incorporated). Methods Forty subjects, aged 21–31 years, who met the inclusion criteria participated. The tested eye was randomised. Two Landolt C sizes (2.68 degrees, 6/194, “small”; 8.58 degrees, 6/619, “large”) were used, with one size and three chromaticities presented per block of trials. Stimulus presentation used the adaptive screening mode, sequentially determining contrast sensitivity for long-, medium-, and short-wavelength stimuli. Subjects were tested with their natural pupil size (range 4–5 mm diameter), then while viewing through a 2.5-mm artificial pupil. Parametric statistical tests were used for comparisons of performance across pupil size and stimulus size. Results Two-way within-subjects ANOVA indicates no interaction between pupil size and stimulus size for any of the three stimulus chromaticities. The main effect of stimulus size was significant for M-cone (F = 6.506, 2-tailed P = .015) and S-cone (F = 67.728, 2-tailed P < .001) stimuli. The main effect of pupil size was significant for all three stimulus chromaticities (L-cone: F = 227.161, M-cone: F = 249.979, S-cone: F = 89.371, 2-tailed P < .001 for all). Conclusion Although CCS was reduced for all three chromaticities and both stimulus sizes with lower retinal illuminance, only S-wavelength cone contrast sensitivity was significantly different for the small versus large stimuli under the 2.5-mm pupil condition in this cohort. Whether CCS in older patients with naturally small pupils changes with an enlarged stimulus or dilated pupils remains to be explored.

The time course of spatial knowledge acquisition for different digital navigation aids

Digital maps on personal devices (e.g., phones) are common tools used to aid navigation. Different types of digital maps can influence spatial knowledge acquisition, and this effect might depend on whether the user interacts with an forward-up or north-up map. In spatial cognition theory, these differences can be used to support either sequential or continuous theories of spatial knowledge acquisition. To test these hypotheses, we compared spatial learning of participants (N = 67) after navigation in a virtual city with either a forward-up map, a north-up map, or a guiding arrow (i.e., a control) as a navigation aid. Critically, participants were tested on landmark recognition tasks and judgments of relative direction (JRDs) after each of four navigation blocks. We also examined mental workload during map usage using eye tracking in terms of the distributions of fixations on the maps. The results indicated that, regardless of navigation aid, participants improved on both landmark recognition and JRD tasks over blocks of trials. In addition, we found an interaction between block and navigation aid. This interaction suggests that participants in the forward-up map group initially produced more JRD errors than the north-up map group but that the two groups performed similarly in later blocks as they became more familiar with the environment. These findings are consistent with the eye-tracking data, which suggested a decrease in mental workload as evidenced by an increase in fixation distributions over blocks of trials. Together, these results suggest that participants with any of these navigation aids perform similarly on some tasks (supporting sequential theory), although the time course of learning may differ between map types (supporting continuous theory).

Distinct beta frequencies reflect categorical decisions

Based on prior findings of content-specific beta synchronization in working memory and decision making, we hypothesized that beta oscillations support the (re-)activation of cortical representations by mediating neural ensemble formation. We found that beta activity in monkey dorsolateral prefrontal cortex (dlPFC) and pre-supplementary motor area (preSMA) reflects the content of a stimulus in relation to the task context, regardless of its objective properties. In duration- and distance-categorization tasks, we changed the boundary between categories from one block of trials to the next. We found that two distinct beta-band frequencies were consistently associated with the two relative categories, with activity in these bands predicting the animals’ responses. We characterized beta at these frequencies as transient bursts, and showed that dlPFC and preSMA are connected via these distinct frequency channels. These results support the role of beta in forming neural ensembles, and further show that such ensembles synchronize at different beta frequencies.

The Psychometric Function for Focusing Attention on Pitch

What is the effect of focusing auditory attention on an upcoming signal tone? Weak signal tones, 40 ms in duration, were presented in 50 dB continuous white noise and were either uncued or cued 82 ms beforehand by a 12 dB SL cue tone of the same frequency and duration as the signal. Signal frequency was either constant for a block of trials or was randomly one of 11 frequencies from 632 to 3140 Hz. Slopes of psychometric functions for detection in single-interval (Yes/No) trials were obtained from three listeners by varying the signal level over a 1–9 dB range. Plots of log(d’) against signal dB were fit by linear functions. Slopes were similar whether signal frequency was constant or varied, as found by D. Green. Slopes for uncued tones increased by 14% to 20% more than predicted by signal energy (i.e., 0.10), as also found previously, whereas slopes for cued tones followed signal energy corrected for an 8 dB sensory threshold. That pre-cues help attention focus rapidly on signal frequency and permit listeners to act as near-ideal detectors of signal energy, which they do not do otherwise, supports a key hypothesis of Grossberg’s ART model that attention guided by conscious awareness can optimize perception.

Microsaccades are directed toward the midpoint between targets in a variably cued attention task

Reliable, noninvasive biomarkers that reveal the internal state of a subject are an invaluable tool for neurological diagnoses. Small fixational eye movements, called microsaccades, are a candidate biomarker thought to reflect a subject's focus of attention [Z. M. Hafed, J. J. Clark, VisionRes. 42, 2533-2545 (2002); R. Engbert, R. Kliegl, VisionRes. 43, 1035-1045 (2003)]. The linkage between the direction of microsaccades and attention has mainly been demonstrated using explicit and unambiguous attentional cues. However, the natural world is seldom predictable and rarely provides unambiguous information. Thus, a useful biomarker must be robust to such changes in environmental statistics. To determine how well microsaccades reveal visual-spatial attention across behavioral contexts, we analyzed these fixational eye movements in monkeys performing a conventional change detection task. The task included two stimulus locations and variable cue validities across blocks of trials. Subjects were adept at the task, showing precise and graded modulations of visual attention for subtle target changes and performing better and faster when the cue was more reliable [J. P. Mayo, J. H. R. Maunsell, J. Neurosci.36, 5353 (2016)]. However, over tens of thousands of microsaccades, we found no difference in microsaccade direction between cued locations when cue variability was high nor between hit and miss trials. Instead, microsaccades were made toward the midpoint of the two target locations, not toward individual targets. Our results suggest that the direction of microsaccades should be interpreted with caution and may not be a reliable measure of covert spatial attention in more complex viewing conditions.

The Active Suppression of a Distractor's Location Can Be Elusive.

Our visual system is inundated with distracting objects that vie for our attention. While visual attention selects relevant information, inhibitory mechanisms might be useful to suppress the locations occupied by irrelevant distractors. Yet, there is a dearth of behavioral evidence for the active suppression of a distractor's location (ASDL) using central cues that provide preliminary information about a distractor's location. In the first two experiments, we attempt to conceptually replicate, using an online platform, experiments that provide evidence of the ASDL. We replicate the distractor cueing effect in a localization task (Experiment 1) wherein responses to targets were faster when a central arrow cued the location of an impending distractor than an empty location. This effect was larger in the first block of trials than it was in the second. In a discrimination task (Experiment 2), unlike previous studies, we found no evidence for an effect of distractor cueing. In Experiment 3, we replaced the central arrow cues with central number cues because arrow cues may elicit a symbolic shift of attention that might offset the ASDL. Once again, the best model was one in which the distractor cueing effect was absent. We replicate these failures to find evidence of the ASDL in two more experiments. The results suggest that the ASDL can be elusive and may be tied to the response system, not attention.

Meridional Attentional Asymmetries in Astigmatic Eyes.

To investigate the impact of attention orientation in young myopic adults with astigmatism. The effect of attention on foveal meridional performance and anisotropy was measured in corrected myopes with various levels of astigmatism (with-the-rule astigmatism ≤ -0.75D, Axis: 180 ± 20) using orientation-based attention. Attention was manipulated by instructing subjects to attend to either the horizontal or the vertical line of a central pre-stimulus (a pulsed cross) along separate blocks of trials. For each attention condition, meridional acuity and reaction times were measured via an annulus Gabor target situated remotely from the cross and presented at random horizontally and vertically in a two-alternative forced-choice employing two interleaved staircase procedures (one-up/one-down). Attention modulations were estimated by the difference in performance between horizontal and vertical attention. Foveal meridional performance and anisotropy were strongly affected by the orientation of attention, which appeared critical for the enhancement of reaction times and resolution. Under congruent orienting of attention, foveal meridional anisotropy was correlated with the amount of defocus for both reaction time and resolution, demonstrating greater vertical performance than horizontal performance as myopia increased. Compatible with an attentional compensation of blur through optimal orienting of attention, vertical attention enhanced reaction times compared to horizontal attention and was accompanied by an increase in overall acuity when myopia increased. Increased astigmatism was associated with smaller attention effects and asymmetry, suggesting potential deficits in the compensation of blur in astigmatic eyes. Collectively, attention to orientation plays a significant role in horizontal-vertical foveal meridional anisotropy and can modulate the asymmetry of foveal perception imposed by the optics of the eye in episodes of uncorrected vision. Further work is necessary to understand how attention and refractive errors interact during visual development. These results may have practical implications for methods to enhance vision with attention training in myopic astigmats.

Ensembles code for associative learning in the primate lateral prefrontal cortex

The lateral prefrontal cortex (LPFC) of primates is thought to play a role in associative learning. However, it remains unclear how LPFC neuronal ensembles dynamically encode and store memories for arbitrary stimulus-response associations. We recorded the activity of neurons in LPFC of two macaques during an associative learning task using multielectrode arrays. During task trials, the color of a symbolic cue indicated the location of one of two possible targets for a saccade. During a trial block, multiple randomly chosen associations were learned by the subjects. A state-space analysis indicated that LPFC neuronal ensembles rapidly learn new stimulus-response associations mirroring the animals' learning. Multiple associations acquired during training are stored in a neuronal subspace and can be retrieved hours after learning. Finally,knowledge of old associations facilitates learning new, similar associations. These results indicate that neuronal ensembles in the primate LPFC provide a flexible and dynamic substrate for associative learning.

Dopaminergic prediction errors in the ventral tegmental area reflect a multithreaded predictive model.

Dopamine neuron activity is tied to the prediction error in temporal difference reinforcement learning models. These models make significant simplifying assumptions, particularly with regard to the structure of the predictions fed into the dopamine neurons, which consist of a single chain of timepoint states. Although this predictive structure can explain error signals observed in many studies, it cannot cope with settings where subjects might infer multiple independent events and outcomes. In the present study, we recorded dopamine neurons in the ventral tegmental area in such a setting to test the validity of the single-stream assumption. Rats were trained in an odor-based choice task, in which the timing and identity of one of several rewards delivered in each trial changed across trial blocks. This design revealed an error signaling pattern that requires the dopamine neurons to access and update multiple independent predictive streams reflecting the subject's belief about timing and potentially unique identities of expected rewards.

Retention of visuo-proprioceptive recalibration in estimating hand position

The brain estimates hand position using visual and proprioceptive cues, which are combined to give an integrated multisensory estimate. Spatial mismatches between cues elicit recalibration, a compensatory process where each unimodal estimate is shifted closer to the other. It is unclear how well visuo-proprioceptive recalibration is retained after mismatch exposure. Here we asked whether direct vision and/or active movement of the hand can undo visuo-proprioceptive recalibration, and whether recalibration is still evident 24 h later. 75 participants performed two blocks of visual, proprioceptive, and combination trials, with no feedback or direct vision of the hand. In Block 1, a 70 mm visuo-proprioceptive mismatch was gradually imposed, and recalibration assessed. Block 2 tested retention. Between blocks, Groups 1–4 rested or made active movements with their directly visible or unseen hand for several minutes. Group 5 had a 24-h gap between blocks. All five groups recalibrated both vision and proprioception in Block 1, and Groups 1–4 retained most of this recalibration in Block 2. Interestingly, Group 5 showed an offline increase in proprioceptive recalibration, but retained little visual recalibration. Our results suggested that visuo-proprioceptive recalibration is robustly retained in the short-term. In the longer term, contextual factors may affect retention.

Ready to go: Higher sense of agency enhances action readiness and reduces response inhibition

Sense of agency is the subjective feeling of being in control of one's actions and their effects. Many studies have elucidated the cognitive and sensorimotor processes that drive this experience. However, less is known about how sense of agency influences flexible cognitive and motor control. Here, we investigated the effect of sense of agency on subsequent action regulation using a modified Go/No-Go task. In Experiment 1, we modulated participants' sense of agency by varying the occurrence of action outcomes (present vs. absent) both locally on a trial-by-trial basis and globally in terms of the overall probability of action outcomes within a block of trials (high vs. low). Importantly, we investigated how this manipulation influenced participants' responses to subsequent Go, No-Go, or Free-Choice cues. When participants' previous action led to an outcome (i.e., a happy face) compared with no outcome, they responded more accurately and faster to Go cues, reacted less accurately to No-Go cues, as well as made go decisions more frequently and faster to Free-Choice cues. These effects were even stronger when action outcomes occurred more frequently overall in a given block or in several previous trials. Experiment 2 further demonstrated that the effects of action outcome manipulation on subsequent action regulation were independent of the emotional valence of the action outcome (i.e., a happy or an angry face). Our results suggest that a higher sense of agency as induced by the presence of action outcomes enhanced action readiness and suppressed response inhibition. These findings highlight the impact of the control felt on the control used in action regulation, thereby providing new insights into the functional significance of the sense of agency on human behavior.

Learning not to attend to distractors if the task is demanding: Constraints on the attentional white bear effect.

Four experiments investigated the attentional white bear (AWB) effect, in which attention increases for an upcoming distractor, and identified two key factors that interact to determine when it occurs: learned attentional set and top-down attentional control. Participants do not show enhanced attention if they begin the experiment with trials that include distractors; the effect only appears in participants who start with a block of trials without distractors. The presence or absence of distractors induces participants to adopt an attentional set that they then maintain when the distractor condition changes. Furthermore, the enhanced attention is only eliminated in the distractor-first participants if the task has a high working memory load. With a low load, the distractor always receives enhanced attention, probably because it poses less competition for resources. The results suggest that participants normally adopt a "process-all" approach, but that top-down attentional control can overrule this approach by suppressing distractor attention if there appear to be insufficient attentional resources to process all the stimuli present. The results show that the AWB effect is subject to attentional control and that a processing strategy adopted as the task is being learned is likely to be maintained even when conditions change. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Individual differences in procedural learning are associated with fiber specific white matter microstructure of the superior cerebellar peduncles in healthy adults

Functional neuroimaging has consistently implicated the fronto-basal ganglia-cerebellar circuit in procedural learning-defined as the incidental acquisition of sequence information through repetition. Limited work has probed the role of white matter fiber pathways that connect the regions in this network, such as the superior cerebellar peduncles (SCP) and the striatal premotor tracts (STPMT), in explaining individual differences in procedural learning. High angular diffusion weighted imaging was acquired from 20 healthy adults aged 18-45 years. Fixel-based analysis was performed to extract specific measures of white matter microstructure (fiber density; FD) and macrostructure (fiber cross-section; FC), from the SCP and STPMT. These fixel metrics were correlated with performance on the serial reaction time (SRT) task, and sensitivity to the sequence was indexed by the difference in reaction time between the final block of sequence trials and the randomized block (namely, the 'rebound effect'). Analyses revealed a significant positive relationship between FD and the rebound effect in segments of both the left and right SCP (pFWE < .05). That is, increased FD in these tracts was associated with greater sensitivity to the sequence on the SRT task. No significant associations were detected between fixel metrics in the STPMT and the rebound effect. Our results support the likely role of white matter organization in the basal ganglia-cerebellar circuit in explaining individual differences in procedural learning.