Perceptual decoupling in the sustained attention to response task is unlikely.

Researchers dispute the cause of errors in high Go, low No Go target detection tasks, like the Sustained Attention to Response Task (SART). Some researchers propose errors in the SART are due to perceptual decoupling, where a participant is unaware of stimulus identity. This lack of external awareness causes an erroneous response. Other researchers suggest the majority of the errors in the SART are instead due to response leniency, not perceptual decoupling. Response delays may enable a participant who is initially unaware of stimulus identity, perceptually decoupled, to become aware of stimulus identity, or perceptually recoupled. If, however, the stimulus presentation time is shortened to the minimum necessary for stimulus recognition and the stimulus is disrupted with a structured mask, then there should be no time to enable perception to recouple even with a response delay. From the perceptual decoupling perspective, there should be no impact of a response delay on performance in this case. Alternatively if response bias is critical, then even in this case a response delay may impact performance. In this study, we shortened stimulus presentation time and added a structured mask. We examined whether a response delay impacted performance in the SART and tasks where the SART's response format was reversed. We expected a response delay would only impact signal detection theory bias, c, in the SART, where response leniency is an issue. In the reverse formatted SART, since bias was not expected to be lenient, we expected no impact or minimal impact of a response delay on response bias. These predictions were verified. Response bias is more critical in understanding SART performance, than perceptual decoupling, which is rare if it occurs at all in the SART.

Perceptual decoupling or trigger happiness: the effect of response delays and shorter presentation times on a go-no-go task with a high go prevalence.

In the current investigation, we modified the high Go, low No-Go Sustained Attention to Response Task (SART). Some researchers argue a commission error, an inappropriate response to a No-Go stimulus, in the SART is due to the participant being inattentive, or perceptually decoupled, during stimulus onset. Response delays in the SART reduce commission errors. A response delay may therefore enable a participant who is initially inattentive to recouple their attention in time to appropriately perceive the stimulus and withhold a response to a No-Go stimulus. However, shortening stimulus display duration in the SART should limit the possibility of the participant identifying the stimulus later, if they are initially not attending the stimulus. A response delay should not reduce commission errors if stimulus duration is kept to the minimum duration enabling stimulus recognition. In two experiments, we shortened stimulus onset to offset duration and added response delays of varying lengths. In both experiments, even when stimulus duration was shortened, response delays notably reduced commission errors if the delay was greater than 250 ms. In addition, using the Signal Detection Theory perspective in which errors of commission in the SART are due to a lenient response bias-trigger happiness, we predicted that response delays would result in a shift to a more conservative response bias in both experiments. These predictions were verified. The errors of commission in the SART may not be a measures of conscious awareness per se, but instead indicative of the level of participant trigger happiness-a lenient response bias.

Response uncertainty influences response bias in the sustained attention to response task: a signal detection theory perspective.

In the current investigation, we modified the high Go, low No-Go Sustained Attention to Response Task (SART) by replacing the single response on Go trials with a dual response to increase response uncertainty. In three experiments, a total of 80 participants completed either the original SART with no response uncertainty regarding the Go stimuli, or versions of the dual response SART in which response probabilities for the two possible responses to the Go stimuli varied from 0.9-0.1, 0.7-0.3, to 0.5-0.5. This resulted in a scale of increasing response uncertainty based on information theory to the Go stimuli. The probability of No-Go withhold stimuli was kept.11 in all experiments. Using the Signal Detection Theory perspective proposed by Bedi et al. (Psychological Research: 1-10, 2022), we predicted that increasing response uncertainty would result in a conservative response bias shift, noted by decreased errors of commission and slower response times to both Go and No-Go stimuli. These predictions were verified. The errors of commission in the SART may not be a measures of conscious awareness per se, but instead indicative of the level of participant trigger happiness-the willingness to respond quickly.

Swimming with a head-mounted display: dual-task costs.

Head-up displays (HUDs) have the potential to change work in operation environments by providing hands-free information to wearers. However, these benefits may be accompanied by trade-offs, primarily by increasing cognitive load due to dividing attention. Previous studies have attempted to understand the trade-offs of HUD usage; however, all of which were focused on land-based tasks. A gap in understanding exists when examining HUD use in aquatic environments as immersion introduces unique environmental and physiological factors that could affect multitasking. In this study, we investigated multitasking performance associated with swimming with a HUD. Eighteen participants completed three tasks: swimming only, a HUD-administered word recall task, and a dual-task combining both tasks. Results revealed significant dual-task interference in both tasks, though possibly less pronounced than in land-based tasks. These findings enhance not only help characterise dual-task performance, but also offer valuable insights for HUD design for aquatic settings.

HUDs have become an increasingly popular tool to present information to users in complex working environments. However, past research examining HUD task performance has been restricted to land-based contexts. The current study examines HUD use while swimming and provides characterisation of multitasking performance within aquatic environments.

Will the real resource theory please stand up! Vigilance is a renewable resource and should be modeled as such.

The vigilance decrement or decline in signal detection performance with time on task is one of the most reliable findings in the cognitive neuroscience and psychology literatures. The majority of theories proposed to explain the decrement are limited cognitive or attention resource based theories; the central nervous system is a limited capacity processor. The decrement in performance is then due to resource reallocation (or misallocation), resource depletion or some combination of both mechanisms. The role of resource depletion, in particular, is hotly debated. However, this may be due to a lack of understanding of the renewable nature of the vigilance resources and how this renewal process impacts performance during vigilance tasks. In the present paper, a simple quantitative model of vigilance resource depletion and renewal is described and shown to generate performance data similar to results seen in both humans and spiders. This model clarifies the role resource depletion and resource renewal may play in vigilance in both people and other animals.

Textbook outcomes and benchmarks of minimally invasive left lateral sectionectomy across North America.

BACKGROUND: Minimally invasive approach represents the gold standard for the resection of the left lateral section of the liver. Recently, the American Minimally Invasive Liver Resection (AMILES) registry has become available to track outcomes of laparoscopic and robotic liver resection in the Americas. The aim of the present study is to determine the benchmark performance of MILLS throughout the AMILES database. METHODS: The AMILES registry was interrogated for cases of minimally invasive left lateral sectionectomies (MILLS). Centers with best practices according to the achievement of textbook outcomes (TOs) were identified and were used to define benchmark performances. RESULTS: Seven institutions from US and Canada entered 1665 minimally invasive liver resections, encompassing 203 MILLS. Overall, 49% of cases of MILLS satisfied contemporarily all textbook outcomes. While all centers obtained TOs with different rates of success, the outcomes of the top-ranking centers were used for benchmarking. Benchmark performance metrics of MILLS across North America are: conversion rate ≤ 3.7%, blood loss ≤ 200 ml, OR time ≤ 199 min, transfusion rate ≤ 4.5%, complication rate ≤ 7.9%, LOS ≤ 4 days. CONCLUSION: Benchmark performances of MILLS have been defined on a large multi-institutional database in North America. As more institutions join the collaboration and more prospective cases accrue, benchmark for additional procedures and approaches will be defined.

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.

Performance, Hemodynamics, and Stress in a Two-Day Vigilance Task: Practical and Theoretical Implications.

OBJECTIVE: To explore vigilance task performance, cerebral blood flow velocity (CBFV), workload, and stress in a within-subjects, two-session experiment. BACKGROUND: Vigilance, or sustained attention, tasks are often characterized by a decline in operator performance and CBFV with time on task, and high workload and stress. Though performance is known to improve with practice, past research has not included measures of CBFV, stress, and workload in a within-subjects multi-session design, which may also provide insight into ongoing theoretical debate. METHOD: Participants performed a vigilance task on two separate occasions. Performance, CBFV, workload, and self-reported stress were measured. RESULTS: Within each session, results were consistent with the vigilance profile found in prior research. Across sessions, performance improved but the time on task decrement remained. Mean CBFV and workload ratings did not differ between sessions, but participants reported significantly less distress, worry, and engagement after session two compared to one. CONCLUSION: Though practice may not disrupt the standard vigilance profile, it may serve to improve overall performance and reduce stress. However, repeated exposure may have negative implications for engagement and mind-wandering. APPLICATION: It is important to better understand the relationship between experience, performance, physiological response, and self-reported stress and workload in vigilance because real-world environments often require operators to do the same task over many occasions. While performance improvement and reduced distress is an encouraging result, the decline in engagement requires further research. Results across sessions fail to provide support to the mind-wandering theory of vigilance.

A Closer Look at Warning Cues on the Sustained Attention to Response Task Performance.

OBJECTIVES: We investigated the effects of auditory cues of varying reliability levels on response inhibition performance using a target detection task to determine if external cues offer performance benefits. Further, we examined how the slope of the speed accuracy trade-off changes as a function of auditory cue reliability and used the trade-off to understand where any performance gains may be realized. BACKGROUND: Researchers have proposed that the sustained attention to response task (SART) can be used to study the mechanisms causing failures of response inhibition. External cues may mitigate the results of motor inhibition failure. The extent to which external cues can effectively aid performance depends on the level of cue reliability. METHOD: Ninety-one participants performed three SARTs with auditory cue assistance at three different levels of reliability (i.e. 0%, 60% and 100% reliable at cueing imminent No-Go stimuli). RESULTS: We observed fewer errors of commission and faster reaction time in conditions with higher cue reliability. The slope of speed-accuracy trade-off relationship was impacted by cue reliability and was not a simple linear function. CONCLUSION: Reliable auditory cues aid performance by reducing reaction time and errors of commission. Auditory cues also impact the relationship between speed and accuracy trade-off. APPLICATION: Insights of cue effectiveness at different reliability levels help people make informed decisions in developing automation interfaces or sensors based on expected performance. Reliable cues mitigate the risk of impulsive errors; however, the reliability has to be high to have a noticeable impact on the speed-accuracy trade-off.

The Role of State and Trait Self-Control on the Sustained Attention to Response Task.

OBJECTIVE: This study aimed to assess the plausibility of self-control depletion, or ego-depletion, as the underlying cognitive resource responsible for performance decrements on the sustained attention to response task. BACKGROUND: Researchers suggested that self-control is a limited cognitive resource used to complete a myriad of processes, including sustained attention. Past research showed that trait self-control affects some sustained attention tasks. However, little research has investigated the effect of self-control as a limited cognitive resource that varies over time (i.e., as a state-dependent variable). METHODS: This experiment investigated the effect of self-control (trait and state) on a sustained motor-inhibition task (e.g., sustained attention to response task; SART). State self-control was manipulated using a between-subjects design-participants in the experimental condition completed a task designed to deplete state self-control prior to performing the SART while the control condition completed a modified version that did not deplete self-control. RESULTS: Trait self-control predicted performance on the SART, but the depletion task (state self-control) had no detectable effect. CONCLUSION: Given the evidence, it is unlikely that state self-control plays a causal role in performance decrements in the SART, but there appears to be some association between performance on the SART and trait self-control. APPLICATION: Trait self-control ought to be considered in future work for personnel selection in real-world tasks that the SART models such as long-distance driving, air traffic control, and TSA operations.

The effects of dual-task interference on visual search and verbal memory.

The operational costs of multitasking are more pressing given the increase in wearable technologies (head-up displays; HUDs) that facilitate multitasking. Often multitasking comes with performance costs, where the addition of more tasks impairs the performance of the tasks. The current study explored the extent to which multitasking interference can be characterised in simulated environments, as opposed to risky and harsh environments in real operational contexts. Forty-eight participants completed several trials where they performed a visual search task while navigating a simulated environment. There were three conditions: a standalone memory task, a standalone search task, and both tasks simultaneously. Results revealed significant dual-task interference when comparing the dual-task to each of the single-tasks. Results were corroborated by subjective workload and stress metrics. The results could prove useful for designing systems for individuals who routinely multitask in operational environments. Specifically, by furthering the understanding of their performance capabilities and trade-offs due to multitasking.Practitioner summary: Due to the demands of multitasking in operational environments, quantifying the degree of information lost on each task individually will aid in the understanding of the deficits of multitasking performance. This study shows that deficits in multi-tasking (via a HUD) can be understood in simulated environments to a similar degree as real-world tasks.

The effects of real-time performance feedback and performance emphasis on the sustained attention to response task (SART).

The sustained attention to response task (SART) has been used for over 20 years to assess participants' response times and inability to withhold to No-Go stimuli (commission errors). While there is debate in the literature regarding what causes commissions errors in the SART, there is agreement the SART is subject to a speed-accuracy trade-off (SATO). Researchers have demonstrated that performance on the SART can be influenced by directive instructions to participants to prioritize either speed or accuracy during the task. In the present study, we investigated whether real-time performance feedback and whether feedback emphasis (emphasizing speed or accuracy) affected participants' response times and accuracy. We found performance feedback per se had no impact on performance, but performance emphasis did affect performance, apparently shifting the SATO. This finding provides further evidence that the commission errors in the SART are not indicative of sustained attention or vigilance as those terms are commonly used in the literature, but more likely assess response strategy and motor control (or lack of motor control). These findings have implications for the psychological assessment literature, as well as applied areas where SART findings have been utilized such as shoot/no-shoot decision making.

Prolonging the Response Movement Reduces Commission Errors in a High-Go, Low-No-Go Target Detection Task and Composite Metrics of Performance Miss This Effect.

OBJECTIVE: Expand research on the Sustained Attention to Response Task (SART) to a more applied agricultural target detection/selection task and examine the utility of various performance metrics, including composite measures of speed and accuracy, in a High-Go/Low-No-Go stimuli task. BACKGROUND: Modified SARTs have been utilized to investigate mechanisms, such as failures of response inhibition, occurring in friendly fire and collateral damage incidents. Researchers have demonstrated that composite measures of speed and accuracy are useful for Low Go/High No-Go stimuli tasks, but this has not been demonstrated for High-Go/Low-No-Go tasks, such as the SART. METHOD: Participants performed a modified SART, where they selected ("sprayed") images of weeds (Go stimuli) that appeared on a computer screen, while withholding to rarer soybean plant images (No-Go stimuli). RESULTS: Response time was a function of distance from a central starting point. Participants committed commission errors (sprayed the soybeans) at a significantly higher rate when the stimuli appeared under the cursor centered on the screen for each trial. Participant's omission errors (failure to spray a weed) increased significantly as a function of distance. The composite measures examined were primarily influenced by response time and omission errors limiting their utility when commission errors are of particular interest. CONCLUSION: Participants are far more accurate in their decision making when required to execute a longer duration motor task in High-Go/Low-No-Go experiments. APPLICATION: Demonstrates a serious human factors liability of target detection and snap-to-target systems.

Dual-Task Interference Between Swimming and Verbal Memory.

OBJECTIVE: A dual-task study was performed to explore the performance effects for swimming, word recall, and the combination of the two tasks performed simultaneously. BACKGROUND: Dual-task interference studies have been performed for a variety of tasks; however, there has not been much dual-task interference research where one of the tasks is a naturalistic physically strenuous task. Swimming is a unique physical task that requires spatial orientation on three dimensional axes, similar to that of flying, but has no risk of falling. Previous studies have been conducted in other activity combinations with word-free recall, such as running and climbing, but swimming has yet to be explored. METHOD: A verbal memory recall task and swimming task were performed in isolated (single-task) and simultaneous conditions. A comparison of effects across these different activities was also explored. RESULTS: Swimming and the word-recall task resulted in significant dual-task interference: almost as much as when word recall was paired with another verbal task, but more than running and less than climbing. CONCLUSION: Consistent with other dual-task studies, this study observed dual-task interference between the physical swimming task and the cognitive verbal memory task. APPLICATION: Future technologies and training for personnel who engage in water rescue or commercial diving, such as underwater welding and fiber optic cable, may be improved by these findings.

Response Complexity Reduces Errors on a Response Inhibition Task.

OBJECTIVE: The purpose of this investigation was to elucidate the role of button-response complexity to targets in a response inhibition task. BACKGROUND: Response inhibition is the ability to correctly inhibit an overt response to a target. The U.S. military is actively pursuing development of armed, combat robots as a force multiplier, which may present challenges to operators of combat robots in the form of response inhibition errors. METHOD: A total of 15 participants completed two 51-min versions of a modified sustained attention to response task (SART). Participants were outfitted with an electrocardiogram to index heart-rate variability and completed the NASA-Task Load Index (NASA-TLX) to index workload. RESULTS: The results demonstrated that the complex SART reduced errors of commission (4%) and slowed response times (874 ms) to correct Go targets relative to the simple SART (14%, 739 ms). The NASA-TLX did not show differences between the modified SARTs; however, heart-rate variability did demonstrate that Soldiers had an increased autonomic stress response to the complex SART. CONCLUSION: Increasing the behavioral response requirement during a response inhibition task can decrease errors of commission; however, it comes at the cost of slower response times to target stimuli. Heart-rate variability may provide better insight into objective workload relative to subjective measures. APPLICATION: The use of complex behavioral responses may provide a viable option to reduce potential "friendly fire" or collateral damage by Soldiers remotely engaging a target-rich environment.

Cue utilisation predicts control room operators' performance in a sustained visual search task.

This research was designed to determine whether qualified practitioners' cue utilisation is predictive of their performance during a sustained visual search task in an operational context. Australian Distribution Network Service Provider (DNSP) operators were recruited for two experiments, and were classified with either higher or lower cue utilisation based on an assessment of cue utilisation within the context of power distribution. Operators' performance was assessed using a domain-related sustained visual search task. In both experiments, power distribution operators with higher cue utilisation demonstrated shorter mean response latencies during the sustained visual search task, compared to operators with lower cue utilisation. Further, no differences in accuracy based on cue utilisation were observed during the sustained visual search task. The results are consistent with the proposition that power operators with higher cue utilisation have a greater capacity to sustain visual search during domain-related tasks, compared to operators with lower cue utilisation. Practitioner summary: Power distribution system operators' cue utilisation was used to predict performance during a domain-related sustained visual search task. Power distribution operators with higher cue utilisation demonstrated shorter mean response latencies during the sustained visual search task, but no differences in accuracy, compared to operators with lower cue utilisation. Abbreviations: DNSP: distribution network service provider; EXPERTise 2.0: EXPERT intensive skills evaluation; FAT: feature association task; FDT: feature discrimination task; FIT: feature identification task; fNIRS: functional near infrared spectroscopy; FPT: feature prioritisation task; FRT: feature recognition task; SCADA: supervisory control and data acquisition.

Does Depleting Self-Control Result in Poorer Vigilance Performance?

OBJECTIVE: To investigate whether depleting self-control prior to vigilance results in a steeper vigilance decrement. BACKGROUND: The resource-control theory of vigilance asserts that an inherent bias toward self-generated mind-wandering draws attentional resources away from the primary task. This study seeks to test whether depleting self-control, the potential mechanism of self-generated mind-wandering, results in poorer vigilance performance. METHOD: This study featured a between-subjects design where participants either completed a typing task that depleted self-control resources or a standard typing task that did not require self-control before performing a vigilance task. In the self-control depletion condition, participants typed a passage while omitting any "e" and "space" keys. In the standard typing task, participants typed the same passage without skipping any keys. Following both typing tasks, participants in both conditions completed an identical 12-min vigilance task. RESULTS: Results demonstrated decreased accuracy and increased reaction times over time for both groups. Depleting self-control did not result in significant differences in accuracy, reaction time, nor a steeper vigilance decrement. CONCLUSION: These results provide evidence against resource-control theory and self-control as an explanation for vigilance, and provide further support for cognitive resource theory as the predominant explanation for vigilance impairments. APPLICATION: It is still unclear exactly what constitutes a "resource." A better understanding of the nature of these resources can help researchers and practitioners identify how they can be replenished, which could enhance human performance in situations requiring vigilance such as baggage screening.

Is Semantic Vigilance Impaired by Narrative Memory Demands? Theory and Applications.

OBJECTIVE: Two verbal tasks were utilized in a dual-task paradigm to explore performance theories and prior dual-tasking results. BACKGROUND: Both the decline in vigilance performance over time, or vigilance decrement, and limited dual-tasking ability may be explained by limited mental resources. Resource theorists would recommend removing task demands to avoid cognitive overload, while mindlessness theorists may recommend adding engaging task demands to prevent boredom. Prior research demonstrated interference between a verbal free recall and semantic vigilance task, but exploring tasks with greater ecological validity is necessary. METHOD: A narrative memory task and semantic vigilance task were performed individually and simultaneously. Relative performance impairments were compared to a previous dual-task pairing. RESULTS: The semantic vigilance task caused performance degradation to the narrative memory task and vice versa. A vigilance decrement was not observed, and the interference was to a lesser extent than when the semantic vigilance task was paired with a free recall task. CONCLUSION: Resource theory was supported, though passive learning effects during a semantic vigilance task with novel stimuli may prevent a vigilance decrement. The interference was less than that of a previous similar dual-task pairing, but even tasks as routine as listening to a conversation or story can impair other task performance. APPLICATION: A better understanding of resource theory and dual-task performance outcomes can help inform feasible task loads and improve efficiency and safety of operators in high-risk and other professions.

Gemcitabine and Taxane Adjuvant Therapy with Chemoradiation in Resected Pancreatic Cancer: A Novel Strategy for Improved Survival?

BACKGROUND: Gemcitabine-taxane combination chemotherapy has demonstrated a survival benefit clinically in metastatic pancreatic cancer (PC). The authors present their experience with gemcitabine and docetaxel (gem/tax)-based adjuvant treatment (Rx) after surgery with curative intent. METHODS: Patients with de novo resectable PC from January 2010 to December 2015 were identified from the authors' institutional database and registry. The study included only patients who received gem/tax as their initial Rx administered exclusively at the authors' institution with or without chemoradiation (CRTx). Survival analysis was performed using Kaplan-Meier methods, and prognostic factors were investigated by Cox proportional hazard modeling. RESULTS: Of 102 patients identified, 58 met the study criteria. The median age at diagnosis was 65 years, with 55% of the patients undergoing an R1 resection (margin ≤ 1 mm). Tumor characteristics included a median tumor size of 28 mm, a poor differentiation rate of 54%, and a lymph node positivity of 67%. Most of the patients (90%, 52/58) completed 80% or more of the 24 week Rx. Of these patients, 71% received post-gem/tax CRTx Rx. Grade 3 or 4 toxicity was observed in 52% of the patients. The median follow-up period was 51.2 months, and the observed median overall survival (OS) was 52 months [95% confidence interval (CI) 27.4-not reached]. The actuarial 5-year OS was 49% (95% CI 33.7-63.4%). In the multivariate analysis, an R1 resection and American Joint Committee on Cancer (AJCC) stage 2 versus stage 1 disease were negatively associated with OS, whereas administration of CRTx was positively associated with OS. CONCLUSIONS: Adjuvant gem/tax with or without CRTx is feasible, with a favorable OS. Future prospective studies of gem/taxane-based adjuvant Rx for PC are warranted.

Psychophysical investigation of vigilance decrement in jumping spiders: overstimulation or understimulation?

The inability to maintain signal detection performance with time on task, or vigilance decrement, is widely studied in people because of its profound implications on attention-demanding tasks over sustained periods of time (e.g., air-traffic control). According to the resource depletion (overload) theory, a faster decrement is expected in tasks that are cognitively demanding or overstimulating, while the underload theory predicts steeper decrements in tasks that provide too little cognitive load, or understimulation. Using Trite planiceps, a jumping spider which is an active visual hunter, we investigated vigilance decrement to repetitive visual stimuli. Spiders were tethered in front of two stimulus presentation monitors and were given a polystyrene ball to hold. Movement of this ball indicates an attempt to turn towards a visual stimulus presented to a pair of laterally facing (anterior lateral) eyes for closer investigation with high acuity forward-facing (anterior median) eyes. Vigilance decrement is easily measured, as moving visual stimuli trigger clear optokinetic responses. We manipulated task difficulty by varying the contrast of the stimulus and the degree of 'noise' displayed on the screen over which the stimulus moved, thus affecting the signal:noise ratio. Additionally, we manipulated motivation by paired testing of hungry and sated spiders. All factors affected the vigilance decrement, but the key variable affecting decrement was stimulus contrast. Spiders exhibited a steeper decrement in the harder tasks, aligning with the resource depletion theory.