Aptitude and attitude: predictors of performance during and after basic laparoscopic skills training.

BACKGROUND: Manual dexterity and visual-spatial ability are considered key to the development of superior laparoscopic skills. Nevertheless, these abilities do not reliably explain all the variance found in the technical performance of surgical trainees. Consequently, we must look beyond these abilities to improve our understanding of laparoscopic skills and to better identify/develop surgical potential earlier on. PURPOSE: To assess the individual and collective impact of physical, cognitive, visual, and psychological variables on performance during and after basic simulation-based laparoscopic skills training. METHOD: Thirty-four medical students (laparoscopic novices) completed a proficiency-based laparoscopic skills training program (using either a 2D or 3D viewing mode). This was followed by one testing session, a follow-up testing session with new (yet similar) tasks, and a series of physical, cognitive, visual, and psychological measures. RESULTS: The statistical models that best predicted variance in training performance metrics included four variables: viewing mode (2D vs 3D), psychological flexibility, perceived task demands, and manual dexterity (bimanual). In subsequent testing, a model that included viewing mode and manual dexterity (assembly) best predicted performance on the pre-practiced tasks. However, for a highly novel, spatially complex laparoscopic task, performance was best predicted by a model that comprised viewing mode, visual-spatial ability, and perceived task demands. At follow-up, manual dexterity (assembly) alone was the best predictor of performance on new (yet similar) tasks. CONCLUSION: By focussing exclusively on physical/cognitive abilities, we may overlook other important predictors of surgical performance (e.g. psychological variables). The present findings suggest that laparoscopic performance may be more accurately explained through the combined effects of physical, cognitive, visual, and psychological variables. Further, the results suggest that the predictors may change with both task demands and the development of the trainee. This study highlights the key role of psychological skills in overcoming initial training challenges, with far-reaching implications for practice.

Laparoscopic skills training: the effects of viewing mode (2D vs. 3D) on skill acquisition and transfer.

BACKGROUND: Three-dimensional (3D) visual displays have been suggested to aid laparoscopic skills training by providing the depth cues not present in traditional two-dimensional (2D) displays. However, few studies have robustly investigated the impact of viewing mode (2D vs. 3D) on learning outcomes. PURPOSE: To examine how viewing mode (2D vs. 3D) impacts the acquisition and transferability of basic laparoscopic skills by comparing performance between transfer and control groups on a complete proficiency-based training program. METHOD: A counterbalanced between-subjects design was employed. Each participant was randomly allocated to one of four groups, comprising two transfer groups (trained in one viewing mode and tested in the alternate mode: the 2D → 3D and 3D → 2D groups) and two control groups (trained and tested in one viewing mode: the 2D → 2D and 3D → 3D groups). Participants completed proficiency-based training in six laparoscopic training tasks. Testing included two further repetitions of all tasks under test conditions. Objective performance measures included the total number of repetitions to reach proficiency, and total performance scores (i.e. time + error penalties across all repetitions) in training and testing. RESULTS: The groups trained in 3D demonstrated superior training performance (i.e. less time + errors) and took fewer repetitions to reach proficiency than the groups trained in 2D. The groups tested in 3D also demonstrated superior test performance compared to those tested in 2D. However, training mode did not yield significant test differences between the groups tested in 2D (i.e. 2D → 2D vs. 3D → 2D), or between the groups tested in 3D (i.e. 3D → 3D vs. 2D → 3D). CONCLUSION: Novices demonstrate superior performance in laparoscopic skills training using a 3D viewing mode compared to 2D. However, this does not necessarily translate to superior performance in subsequent testing or enhanced learning overall. Rather, test performance appears to be dictated by the viewing mode used during testing, not that of prior training.

Temporal dynamics of a perceptual decision.

Previous research suggests that cognitive factors acting in a top-down manner influence the perceptual interpretation of ambiguous stimuli. To examine the temporal unfolding of these influences as a perceptual decision evolves, we have implemented a modified version of the stream-bounce display. Our novel approach allows us to track responses to stream-bounce stimuli dynamically over the entire course of the motion sequence rather than collecting a subjective report after the fact. Using a trackpad, we had participants control a cursor to track a stream-bounce target actively from start to end and measured tracking speed throughout as the dependent variable. Our paradigm replicated the typical effect of visual-only displays being associated with a streaming bias and audiovisual displays with a bouncing bias. Our main finding is a significant behavioral change preceding a perceptual decision that then predicts that decision. Specifically, for trials in which the sound was presented, tracking speeds were significantly slower starting 500 ms before the point of coincidence and presentation of the sound for bounce compared to stream responses. We suggest that behavioral response may reflect a cognitive expectation of a perceptual outcome that then biases action and the interpretation of sensory input to favor that forthcoming percept in a manner consistent with both the predictive-coding and common-coding theoretical frameworks. Our approach provides a novel behavioral corroboration of recent imaging studies that are suggestive of early brain activity in perception and action.

The Effect of Transient Location on the Resolution of Bistable Visual and Audiovisual Motion Sequences.

We examined the attention and inference accounts of audiovisual perception using the stream/bounce display, a visual stimulus wherein two identical objects move toward each other, completely superimpose, then move apart. This display has two candidate percepts: stream past each other or bounce off each other. Presented without additional visual or auditory transients, the motion sequence tends to yield the streaming percept, but when coupled with a tone or flash at the point of coincidence, the response bias flips toward bouncing. We explored two competing accounts of this effect: the attentional hypothesis and the inference hypothesis. Participants watched a series of motion sequences where a transient, when present, occurred at the moment of coincidence either colocalised with the motion sequence (congruent presentation) or on the opposite side of the display (incongruent presentation). Assuming the spotlight or zoom lens metaphor, an attentional account predicts that incongruent presentations should be associated with a higher percentage of bouncing responses than congruent presentations, while the inferential account predicts the opposite effect. No effect was found for tone-only trials. However, in trials containing a visual transient, results showed higher proportions of bounce responses within congruent over incongruent presentations, favouring the inference hypothesis over a spotlight or zoom lens attentional account.

The impact of crosstalk on three-dimensional laparoscopic performance and workload.

This is the first study to explore the effects of crosstalk from 3D laparoscopic displays on technical performance and workload. We studied crosstalk at magnitudes that may have been tolerated during laparoscopic surgery. Participants were 36 voluntary doctors. To minimize floor effects, participants completed their surgery rotations, and a laparoscopic suturing course for surgical trainees. We used a counterbalanced, within-subjects design in which participants were randomly assigned to complete laparoscopic tasks in one of six unique testing sequences. In a simulation laboratory, participants were randomly assigned to complete laparoscopic 'navigation in space' and suturing tasks in three viewing conditions: 2D, 3D without ghosting and 3D with ghosting. Participants calibrated their exposure to crosstalk as the maximum level of ghosting that they could tolerate without discomfort. The Randot® Stereotest was used to verify stereoacuity. The study performance metric was time to completion. The NASA TLX was used to measure workload. Normal threshold stereoacuity (40-20 second of arc) was verified in all participants. Comparing optimal 3D with 2D viewing conditions, mean performance times were 2.8 and 1.6 times faster in laparoscopic navigation in space and suturing tasks respectively (p< .001). Comparing optimal 3D with suboptimal 3D viewing conditions, mean performance times were 2.9 times faster in both tasks (p< .001). Mean workload in 2D was 1.5 and 1.3 times greater than in optimal 3D viewing, for navigation in space and suturing tasks respectively (p< .001). Mean workload associated with suboptimal 3D was 1.3 times greater than optimal 3D in both laparoscopic tasks (p< .001). There was no significant relationship between the magnitude of ghosting score, laparoscopic performance and workload. Our findings highlight the advantages of 3D displays when used optimally, and their shortcomings when used sub-optimally, on both laparoscopic performance and workload.

Sensitivity and Bias in the Resolution of Stream-Bounce Stimuli.

The audiovisual stream-bounce effect refers to the resolution of ambiguous motion sequences as streaming or bouncing depending on the presence or absence of a sound. We used a novel experimental design and signal detection theory (SDT) to determine its sensory or decisional origins. To account for issues raised by Witt et al. on the interpretation of SDT results, we devised a pure signal detection (as opposed to signal discrimination) paradigm and measured participants' sensitivity and criterion when detecting a weak tone concurrent with objectively streaming or bouncing visual displays. We observed no change in sensitivity but a significant change in criterion with participants' criterion more liberal with bouncing targets than for streaming targets with. In a second experiment, we tasked participants with detecting a weak tone in noise while viewing an ambiguous motion sequence. They also indicated whether the targets appeared to stream or bounce. Participants' reported equivalent, mostly bouncing responses for hit and false alarm trials, and equivalent, mostly streaming responses for correct rejection and miss trials. Further, differences in participants' sensitivity and criterion measures for detecting tones in subjectively streaming compared to subjectively bouncing targets were inconsistent with sensory factors. These results support a decisional account of the sound-induced switch from mostly streaming to mostly bouncing responses in audiovisual stream-bounce displays.

Low-Level Motion Characteristics Do Not Account for Perceptions of Stream-Bounce Stimuli.

The stream-bounce effect refers to a bistable motion stimulus that is interpreted as two targets either "streaming" past or "bouncing" off one another, and the manipulations that bias responses. Directional bias, according to Bertenthal et al., is an account of the effect proposing that low-level motion integration promotes streaming, and its disruption leads to bouncing, and it is sometimes cited either directly in a bottom-up fashion or indirectly under top-down control despite Sekuler and Sekuler finding evidence inconsistent with it. We tested two key aspects of the hypothesis: (a) comparable changes in speed should produce comparable disruptions and lead to similar effects; and (b) speed changes alone should disrupt integration without the need for additional more complex changes of motion. We found that target motion influences stream-bounce perception, but not as directional bias predicts. Our results support Sekuler and Sekuler and argue against the low-level motion signals driving perceptual outcomes in stream-bounce displays (directly or indirectly) and point to higher level inferential processes involving perceptual history and expectation. Directional bias as a mechanism should be abandoned and either another specific bottom-up process must be proposed and tested or consideration should be given to top-down factors alone driving the effect.

The Conflicting Evidence of Three-dimensional Displays in Laparoscopy: A Review of Systems Old and New.

OBJECTIVE: To describe studies evaluating 3 generations of three-dimensional (3D) displays over the course of 20 years. SUMMARY BACKGROUND DATA: Most previous studies have analyzed performance differences during 3D and two-dimensional (2D) laparoscopy without using appropriate controls that equated conditions in all respects except for 3D or 2D viewing. METHODS: Databases search consisted of MEDLINE and PubMed. The reference lists for all relevant articles were also reviewed for additional articles. The search strategy employed the use of keywords "3D," "Laparoscopic," "Laparoscopy," "Performance," "Education," "Learning," and "Surgery" in appropriate combinations. RESULTS: Our current understanding of the performance metrics between 3D and 2D laparoscopy is mostly from the research with flawed study designs. This review has been written in a qualitative style to explain in detail how prior research has underestimated the potential benefit of 3D displays and the improvements that must be made in future experiments comparing 3D and 2D displays to better determine any advantage of using one display or the other. CONCLUSIONS: Individual laparoscopic performance in 3D may be affected by a multitude of factors. It is crucial for studies to measure participant stereoscopic ability, control for system crosstalk, and use validated measures of performance.

The viewpoint-specific failure of modern 3D displays in laparoscopic surgery.

PURPOSE: Surgeons conventionally assume the optimal viewing position during 3D laparoscopic surgery and may not be aware of the potential hazards to team members positioned across different suboptimal viewing positions. The first aim of this study was to map the viewing positions within a standard operating theatre where individuals may experience visual ghosting (i.e. double vision images) from crosstalk. The second aim was to characterize the standard viewing positions adopted by instrument nurses and surgical assistants during laparoscopic pelvic surgery and report the associated levels of visual ghosting and discomfort. METHODS: In experiment 1, 15 participants viewed a laparoscopic 3D display from 176 different viewing positions around the screen. In experiment 2, 12 participants (randomly assigned to four clinically relevant viewing positions) viewed laparoscopic suturing in a simulation laboratory. In both experiments, we measured the intensity of visual ghosting. In experiment 2, participants also completed the Simulator Sickness Questionnaire. RESULTS: We mapped locations within the dimensions of a standard operating theatre at which visual ghosting may result during 3D laparoscopy. Head height relative to the bottom of the image and large horizontal eccentricities away from the surface normal were important contributors to high levels of visual ghosting. Conventional viewing positions adopted by instrument nurses yielded high levels of visual ghosting and severe discomfort. CONCLUSIONS: The conventional viewing positions adopted by surgical team members during laparoscopic pelvic operations are suboptimal for viewing 3D laparoscopic displays, and even short periods of viewing can yield high levels of discomfort.

Binocular correspondence and the range of fusible horizontal disparities in the central visual field.

Binocular disparities underlie precise stereoscopic depth perception but only over a finite range. At large disparities, objects appear diplopic, and depth perception is degraded. Measurements of the range of horizontal disparities for which single vision is experienced have previously been restricted to the horizontal plane of regard. We extended these mappings, in two experiments, to the upper and lower visual fields and eccentric meridians. In Experiment 1, we measured empirical corresponding points and fusional limits at identical elevations in the median plane for 20 participants. We observed a vertical shear in binocular correspondence consistent with a backward inclined empirical vertical horopter and the fusional range centered upon it. In Experiment 2, we mapped the vertical horopter and fusional limits for a second set of elevations in the median plane and at two additional eccentricities and found a similar pattern of results as in Experiment 1. For 23 of 25 participants in this study, we found that the relationship between measurements of the vertical horopter and fusional range is similar to the established relationship between Panum's fusional range and the horizontal horopter. Our data replicate previous findings that the vertical horopter is inclined top back. We are the first to illustrate that the fusional range of horizontal disparities is approximately centered upon the vertical horopter in the median plane and along eccentric meridians.

A single auditory tone alters the perception of multiple visual events.

We aimed to show that a single auditory tone crossmodally affects multiple visual events using a multiple stream/bounce display (SBD), consisting of two disk pairs moving toward each other at equal speeds, coinciding, and then moving apart in a two-dimensional (2-D) display. The temporal offsets were manipulated between the coincidences of the disk pairs (0 to ±240 ms) by staggering motion onset between the pairs. A tone was presented at the coincidence timing of one of the disk pairs on half of the trials. Participants judged whether the disks in each of two pairs appeared to stream through or bounce off each other. Results show that a tone presented at either of the disk pairs' coincidence points promoted bouncing percepts in both disk pairs compared to no-tone trials. Perceived bouncing persisted in the disk-pair whose coincidence was offset 60 ms before and up to more than 120 ms after the audiovisual coincidence timing of the other disk-pair. The temporal window of bounce promotion was comparable to that obtained with a conventional SBD. The interaction of a single auditory event and multiple visual events was also modulated by the kind of experimental task (the stream/bounce or simultaneity judgments). These findings suggest that, using a single auditory cue, the perceptual system resolves the ambiguity of the motion of multiple disk pairs presented within the conventional temporal window of crossmodal interaction.

Segmentation by depth does not always facilitate visual search.

In visual search, target detection times are relatively insensitive to set size when targets and distractors differ on a single feature dimension. Search can be confined to only those elements sharing a single feature, such as color (Egeth, Virzi, & Garbart, 1984). These findings have been taken as evidence that elementary feature dimensions support a parallel segmentation of a scene into discrete sets of items. Here we explored if relative depth (signaled by binocular disparity) could support a similar parallel segmentation by examining the effects of distributing distracting elements across two depth planes. Three important empirical findings emerged. First, when the target was a feature singleton on the target depth plane, but a conjunction search among distractors on the nontarget plane, search efficiency increased compared to a single depth plane. Second, benefits of segmentation in depth were only observed when the target depth plane was known in advance. Third, no benefit of segmentation in depth was observed when both planes required a conjunction search, even with prior knowledge of the target depth plane. Overall, the benefit of distributing the elements of a search set across two depth planes was observed only when the two planes differed both in binocular disparity and in the elementary feature composition of individual elements. We conclude that segmentation of the search array into two depth planes can facilitate visual search, but unlike color or other elementary properties, does not provide an automatic, preattentive segmentation.

Impact of acute open-skill exercise on inhibitory control and brain activation: A functional near-infrared spectroscopy study.

There is a growing body of literature demonstrating that a single bout of exercise benefits executive cognitive function. While the acute effect of closed-skill exercises like walking, running, and cycling has been well investigated, it is less clear how open-skill exercise impacts executive function and brain activation. Therefore, we compared the acute effects of an open-skill exercise on inhibitory control and brain activation with those of a closed-skill exercise using functional near-infrared spectroscopy (fNIRS). Twenty-four young right-hand dominant adults (9 women) completed three interventions: badminton, running, and a seated rest control condition for 10 min each. The intensities of badminton and running were comparable. During each intervention, oxygen uptake and heart rate were monitored. A Stroop task composed of neutral and incongruent conditions was administrated before and after each intervention. An fNIRS system recorded hemodynamics in the prefrontal cortex to evaluate brain activation during the Stroop task. Performance on the Stroop task was significantly improved after badminton, specifically in the incongruent condition relative to in the neutral condition. On the other hand, neither running nor seated rest affected performance in the Stroop task. The fNIRS measures indicated that badminton and running had no significant influence on brain activation. These results show that a single bout of open-skill exercise enhances inhibitory control without increasing brain activation compared to closed-skill exercise, suggesting that an acute open-skill exercise induces neural efficiency.

The role of presentation method and depth singletons in visual search for objects moving in depth.

Are objects moving in depth searched for efficiently? Previous studies have reported conflicting results, with some finding efficient search for only approaching motion (Franconeri & Simons, 2003), and others reporting that both approaching and receding motion are found more efficiently than static targets (Skarratt, Cole, & Gellatly, 2009). This may be due to presentation protocol differences and a confounding variable. We systematically tested the effect of the motion-in-depth presentation method and the effect of a confounding unique depth singleton on search performance. Simulating motion in depth using size scaling, changing binocular disparity, or a calibrated combination of these two depth cues, we found that search performance was affected by presentation method and that a combination of size scaling and changing disparity gives rise to the most compelling motion-in-depth perception. Exploiting this finding in Experiment 2, we found that removing the depth singleton does not affect motion-in-depth search performance. Overall, we found that search is more efficient for targets moving in depth than static targets. Approaching and receding motion had an equal advantage over static targets in target selection, shown through shallower search slopes. However, approaching motion had lower intercepts, consistent with an advantage over receding motion in later stages of processing associated with target identification and response.

Auditory transients do not affect visual sensitivity in discriminating between objective streaming and bouncing events.

With few exceptions, the sound-induced bias toward bouncing characteristic of the stream/bounce effect has been demonstrated via subjective responses, leaving open the question whether perceptual factors, decisional factors, or some combination of the two underlie the illusion. We addressed this issue directly, using a novel stimulus and signal detection theory to independently characterize observers' sensitivity (d') and criterion (c) when discriminating between objective streaming and bouncing events in the presence or absence of a brief sound at the point of coincidence. We first confirmed that sound-induced motion reversals persist despite rendering the targets visually distinguishable by differences in texture density. Sound-induced bouncing persisted for targets differing by as many as nine just-noticeable-differences (JNDs). We then exploited this finding in our signal detection paradigm in which observers discriminated between objective streaming and bouncing events. We failed to find any difference in sensitivity (d') between sound and no-sound conditions, but we did observe a significantly more liberal criterion (c) in the sound condition than the no-sound condition. The results suggest that the auditory-induced bias toward bouncing in this context is attributable to a sound-induced shift in criterion implicating decisional processes rather than perceptual processes determining responses to these displays.

Implicit expectation modulates multisensory perception.

Stimulus statistics can induce expectations that in turn can influence multisensory perception. In three experiments, we manipulate perceptual history by biasing stimulus statistics and examined the effect of implicit expectations on the perceptual resolution of a bistable visual stimulus that is modulated by sound. First, we found a general effect of expectation such that responses were biased in line with the biased statistics and interpret this as a bias towards an implicitly expected outcome. Second, expectation did not influence the perception of all types of stimuli. In both Experiment 1 and Experiment 2, integrated audio-visual stimuli were affected by expectation but visual-only and unintegrated audio-visual stimuli were not. In Experiment 3 we examined the sensory versus interpretational effects of expectation and found that contrary to our predictions, an expectation of audio-visually integrated stimuli was associated with impaired multisensory integration compared to visual-only or unintegrated audio-visual stimuli. Our findings suggest that perceptual experience implicitly creates expectations that influence multisensory perception, which appear to be about perceptual outcomes rather than sensory stimuli. Finally, in the case of resolving perceptual ambiguity, the expectation effect is an effect on cognitive rather than sensory processes.

The effects of recent perceptual history on stream-bounce perception.

We examine perceptual disambiguation and crossmodal interactions by considering the effect of recent perceptual history on stream-bounce perception. First, we tested the assumption that the audio-visual stream-bounce effect (visual-only trials mostly stream, whereas audio-visual trials mostly bounce) reflects some intrinsic preference for streaming that is broken by sound. Instead, we found that for naïve observers, visual-only stimuli are bistable and bias free. In intermixed trials, sound acts as a polarizing factor (rather than a bounce-inducing factor) and has as much effect on visual-only trials as it does on audio-visual trials. Second, temporal context exerts a comparative influence and exposure to audio-visual stimuli influences responses to visual-only stimuli and vice-versa. Finally, there is a serial dependence in responses and the current stimulus (unisensory or multisensory) is interpreted with a bias to recent interpretations. Recent perceptual history exerts a substantial influence on the perception of stream-bounce stimuli. This influence occurs in the unisensory case and is in line with an extensive literature on visual bistability; it extends to the multisensory case, and there are interactions between the 2 cases. Our combined findings support a role for top-down interpretational influences in the stream-bounce effect and stream-bounce perception more generally. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

The vergence horopter.

The horopter is defined by the criterion with which it is measured; these include the apparent frontoparallel plane, the region of binocular single vision, and identical visual direction. Another criterion is one that "the positions of the points are such that none provides a stimulus for fusional movement of the eyes". Measuring the horopter using this criterion is the aim of the current paper. Based on previous research investigating corresponding points, we predicted the vergence horopter should trace an arc similar to the empirical horizontal horopter. We further predicted based on the characteristics of vergence eye movements in the periphery, that the range of horizontal disparities that do not elicit a vergence movement would increase with eccentricity. In experiment 1 we conducted the first measurements of the vergence horopter along the horizontal plane of regard and sagittal planes. We found that the vergence horopter consists of a stable range of disparities that do not increase with eccentricity. In experiment 2, we measured Panum's fusional range for the same eccentricities and elevations to determine the placement of the vergence horopter within the fusional ranges. In the horizontal plane, the vergence horopter sits centrally within Panum's fusional range. In the vertical plane, the data are suggestive that the vergence horopter is less slanted than the corresponding fusional range.