Variability of dot spread is overestimated.

Previous research has demonstrated that individuals exhibit a tendency to overestimate the variability of both low-level features (e.g., color, orientation) and mid-level features (e.g., size) when items are presented dynamically in a sequential order, a finding we will refer to as the variability overestimation effect. Because previous research on this bias used sequential displays, an open question is whether the effect is due to a memory-related bias or a vision-related bias. To assess whether the bias would also be apparent with static, simultaneous displays, and to examine whether the bias generalizes to spatial properties, we tested participants' perception of the variability of a cluster of dots. Results showed a consistent overestimation bias: Participants judged the dots as being more spread than they actually were. The variability overestimation effect was observed when there were 10 or 20 dots but not when there were 50 dots. Taken together, the results of the current study contribute to the ensemble perception literature by providing evidence that simultaneously presented stimuli are also susceptible to the variability overestimation effect. The use of static displays further demonstrates that this bias is present in both dynamic and static contexts, suggesting an inherent bias existent in the human visual system. A potential theoretical account-boundary effect-is discussed as a potential underlying mechanism. Moreover, the present study has implications for common visual tasks carried out in real-world scenarios, such as a radiologist making judgments about distribution of calcification in breast cancer diagnoses.

Visual bias could impede diagnostic accuracy of breast cancer calcifications.

Purpose: Diagnosing breast cancer based on the distribution of calcifications is a visual task and thus prone to visual biases. We tested whether a recently discovered visual bias that has implications for breast cancer diagnosis would be present in expert radiologists, thereby validating the concern of this bias for accurate diagnoses. Approach: We ran a vision experiment with expert radiologists and untrained observers to test the presence of visual bias when judging the spread of dots that resembled calcifications and when judging the spread of line orientations. We calculated visual bias scores for both groups for both tasks. Results: Participants overestimated the spread of the dots and the spread of the line orientations. This bias, referred to as the variability overestimation effect, was of similar magnitudes in both expert radiologists and untrained observers. Even though the radiologists were better at both tasks, they were similarly biased compared with the untrained observers. Conclusions: The results justify the concern of the variability overestimation effect for accurate diagnoses based on breast calcifications. Specifically, the bias is likely to lead to an increased number of false-negative results, thereby leading to delayed treatments.

An Objective Measure of Decisional Clarity to Assess Decision Aid Effectiveness in Situations with Equipoise: A Randomized Trial.

BACKGROUND: Decision aids can help patients make medical decisions, which is especially advantageous in situations with equipoise. However, when there is no correct answer, it is difficult to assess whether a decision aid is helpful. The goal of this research is to propose and validate an objective method for measuring decision aid effectiveness by quantifying the clarity participants achieved when making decisions. DESIGN: The measure of decisional clarity was tested in a convenience sample of 131 college-aged students making hypothetical decisions about 2 treatment options for depression and anxiety. The treatments varied with respect to potential benefits and harms. Information was presented numerically or with an accompanying data visualization (an icon array) that is known to aid decision making. RESULTS: Decisional clarity was better with the icon arrays. Furthermore, the results showed that decisional clarity can be used to identify situations for which patients will be more likely to struggle making their decision. These included situations for which financial considerations were relevant to the decision and situations for which the probabilities of potential benefits were higher. LIMITATIONS: The measure of decisional clarity and the situations identified as lacking clarity should be validated with a larger, more representative sample. CONCLUSIONS: These findings demonstrate that decisional clarity can be used to both empirically evaluate the effectiveness of a decision aid as well as test factors that can cloud clarity and disrupt medical decision making. IMPLICATIONS: Researchers and medical providers interested in developing decision aids for situations with equipoise can use decisional clarity as an objective measure to assess the effectiveness of their decision aid. Financial considerations and higher probabilities may also cloud judgments. HIGHLIGHTS: An objective measure of decisional clarity is supported.Decisional clarity can be used to evaluate decision aids in the context of equipoise for which there is no objectively correct choice.Decisional clarity can also be used to identify scenarios for which patients are likely to struggle to make a medical decision.

Visualizing temperature trends: Higher sensitivity to trend direction with single-hue palettes.

Design plays a key role in the interpretability of complex visualizations. Many applied domains utilize large quantities of data to make predictions, ranging from maps showing the spread of infectious disease to line graphs displaying global temperature changes. These visualizations tap into the visual system's ability to extract information from groups of similar objects, a process known as ensemble processing, and the cognitive system's ability to relate visual features such as color to meaningful concepts such as disease or temperature. Visualizations must consider both perceptual and cognitive abilities. It remains unclear which best improves comprehension: visualizations designed to exploit ensemble processes or that use semantically resonant colors that align with the underlying data. To address this question, participants were shown visualizations designed for ensemble processes in that they used color encodings with only a single hue or designed for semantic processes in that they prioritized color alignment with the meaning of the data. Participants viewed stripplots using these colors and judged whether the temperature depicted in the graphs was increasing or decreasing. As quantified using the signal detection measure d', participants' sensitivity to trend information was higher with the single-hue palettes than with more semantically expressive multihue palettes. Our results suggest that visualizations may convey trend information more effectively by selecting colors that exploit ensemble processes rather than selecting semantically compatible colors. Moreover, our results showed semantic compatibility had no effect on sensitivity to trend direction. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Dynamic ensemble visualizations to support understanding for uncertain trajectories.

When making decisions about uncertain spatial trajectories, such as storm forecasts, people rely on visualizations to support their understanding. Four experiments explored novel visualizations-dynamic ensembles. Nonexperts used visualizations to interpret probabilistic information about potential paths of a hurricane. Experiment 1 focused on global properties of the distribution, and showed dynamic ensembles imply a larger area at risk than traditional cones of uncertainty. Experiment 2 compared decisions with cones versus dynamic ensembles at specific individual locations. Dynamic ensembles offer more appreciation of risk outside the center of the distribution, and less abrupt in transitions from evacuation to nonevacuation choices. Experiment 3 compared decisions for dynamic ensembles versus static line ensembles. Similar evacuation rates across the two conditions suggest ensembles, rather than dynamics, are the more critical feature. Experiment 4 examined whether an additional dimension can be included in dynamic ensembles using color coding. Decisions reacted to this ancillary feature, with higher evacuation rates for locations threatened by more severe outcomes. Outcomes highlight the ability to systematically vary the level of risk communicated through the ensembles while also communicating the continuous nature of the risk. The overall findings show the viability of presenting uncertain spatial information using dynamic ensembles. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The Weighted Average Illusion: Biases in Perceived Mean Position in Scatterplots.

Scatterplots can encode a third dimension by using additional channels like size or color (e.g. bubble charts). We explore a potential misinterpretation of trivariate scatterplots, which we call the weighted average illusion, where locations of larger and darker points are given more weight toward x- and y-mean estimates. This systematic bias is sensitive to a designer's choice of size or lightness ranges mapped onto the data. In this paper, we quantify this bias against varying size/lightness ranges and data correlations. We discuss possible explanations for its cause by measuring attention given to individual data points using a vision science technique called the centroid method. Our work illustrates how ensemble processing mechanisms and mental shortcuts can significantly distort visual summaries of data, and can lead to misjudgments like the demonstrated weighted average illusion.

Tool Use Affects Spatial Perception.

Tools do not just expand our capabilities. They change what we can do, and in doing so, they change who we are. Serena is Serena because of what she can do with a tennis racket. Tiger is Tiger because of what he can do with a golf club. In changing what we can do, tools also change the very way we perceive the spatial layout of the world. Objects beyond arm's reach appear closer when we wield a tool that can expand out to the object. Catchable objects seem to move faster when we wield a tool that is less effective for catching the object. These examples illustrate how the basic processes of spatial vision are impacted by tool use.

Better sensitivity to linear and nonlinear trends with position than with color.

Useful data visualizations have the potential to leverage the visual system's natural abilities to process and summarize simple and complex information. Here, we tested whether the design recommendations made for pairwise comparisons generalize to the detection of trends. We created two different types of graphs: line graphs and stripplots. These graphs were created from identical datasets that simulated temperature changes across time. These datasets varied in the type of trend (linear and exponential). Human observers performed a trend detection task for which they judged whether the trend in temperature over time was increasing or decreasing. Participants were more sensitive to trend direction with line graphs compared to stripplots. Participants also demonstrated a systematic bias to respond that the trend was increasing for line graphs. However, this bias decreased with increasing sensitivity. Despite the better sensitivity to line graphs, more than half of the participants found the stripplots more appealing and liked them more than the line graphs. In conclusion, our results indicate that, for trend detection, depicting data with position (line graphs) leads to better performance compared to depicting graphs with color (stripplots). Yet, graphs with color (stripplots) were preferred over the line graphs, suggesting that there may be a tradeoff between the aesthetic design of the graphs and the precision in communicating the information.

Putting the Self in Self-Correction: Findings From the Loss-of-Confidence Project.

Science is often perceived to be a self-correcting enterprise. In principle, the assessment of scientific claims is supposed to proceed in a cumulative fashion, with the reigning theories of the day progressively approximating truth more accurately over time. In practice, however, cumulative self-correction tends to proceed less efficiently than one might naively suppose. Far from evaluating new evidence dispassionately and infallibly, individual scientists often cling stubbornly to prior findings. Here we explore the dynamics of scientific self-correction at an individual rather than collective level. In 13 written statements, researchers from diverse branches of psychology share why and how they have lost confidence in one of their own published findings. We qualitatively characterize these disclosures and explore their implications. A cross-disciplinary survey suggests that such loss-of-confidence sentiments are surprisingly common among members of the broader scientific population yet rarely become part of the public record. We argue that removing barriers to self-correction at the individual level is imperative if the scientific community as a whole is to achieve the ideal of efficient self-correction.

The Pong Effect as a Robust Visual Illusion: Evidence From Manipulating Instructions.

Visual perception is not always veridical but can be influenced by factors such as ease of acting, energetic cost, and even body type of the observer. This notion is called action-specific perception. Several effects of action capability on visual perception have been found, but there is much controversy as to whether these effects are truly perceptual. Because perception cannot be measured directly, resolving the controversy relies on ruling out alternative explanations through systematic testing. We combined one of the most robust action-specific effects (the Pong effect) with one of the primary suggestions for exploring an alternative explanation, namely whether the effect persists across instructions that emphasize different aspects of the task. The Pong effect was robust to the type of instructions. The results provide critical evidence that the Pong effect is truly perceptual, furthering the argument that a person's ability to act can influence visual perception.

Wielding a gun increases judgments of others as holding guns: a randomized controlled trial.

The gun embodiment effect is the consequence caused by wielding a gun on judgments of whether others are also holding a gun. This effect could be responsible for real-world instances when police officers shoot an unarmed person because of the misperception that the person had a gun. The gun embodiment effect is an instance of embodied cognition for which a person's tool-augmented body affects their judgments. The replication crisis in psychology has raised concern about embodied cognition effects in particular, and the issue of low statistical power applies to the original research on the gun embodiment effect. Thus, the first step was to conduct a high-powered replication. We found a significant gun embodiment effect in participants' reaction times and in their proportion of correct responses, but not in signal detection measures of bias, as had been originally reported. To help prevent the gun embodiment effect from leading to fatal encounters, it would be useful to know whether individuals with certain traits are less prone to the effect and whether certain kinds of experiences help alleviate the effect. With the new and reliable measure of the gun embodiment effect, we tested for moderation by individual differences related to prior gun experience, attitudes, personality, and factors related to emotion regulation and impulsivity. Despite the variety of these measures, there was little evidence for moderation. The results were more consistent with the idea of the gun embodiment effect being a universal, fixed effect, than being a flexible, malleable effect.

The Precision-Bias Distinction for Evaluating Visual Decision Aids for Risk Perception.

Risk communication is critically important, for both patients and providers. However, people struggle to understand risks because there are inherent biases and limitations to reasoning under uncertainty. A common strategy to enhance risk communication is the use of decision aids, such as charts or graphs, that depict the risk visually. A problem with prior research on visual decision aids is that it used a metric of performance that confounds 2 underlying constructs: precision and bias. Precision refers to a person's sensitivity to the information, whereas bias refers to a general tendency to overestimate (or underestimate) the level of risk. A visual aid is effective for communicating risk only if it enhances precision or, once precision is suitably high, reduces bias. This article proposes a methodology for evaluating the effectiveness of visual decision aids. Empirical data further illustrate how the new methodology is a significant advancement over more traditional research designs.

Human and machine: Evaluating whether action automation influences visual perception.

The action-specific account of perception suggests that our perceptual system is influenced by information about our ability to act in our environment and, thus, affects our perception. However, the specific information about action that is influential for perception is still largely unknown. For example, if a goal is achieved through automation rather than action, is perception influenced because the goal was achieved or is perception immune because the act was automated rather than performed by the observer? In four experiments, we examined whether automating a paddle to block a moving ball in a computer game similar to Pong affects perception of the ball's speed. Results indicate that the automation used here did not affect speed perception of the target. Whereas tools such as reach-extending sticks and various-sized paddles are both incorporated into one's body schema and also influence spatial perception, automation, our results imply that automation is not incorporated into one's body schema and does not affect spatial perception. The dissociation in how the mind treats tools versus automation could have several implications as automation becomes more prevalent in daily life.

Action's influence on spatial perception: resolution and a mystery.

Despite the impression that perception of spatial layout including distance, slant, and size is objective and geometrically accurate, spatial perception is influenced by a perceiver's ability to act. Hills appear steeper when the perceiver is fatigued, and balls appear faster when they are harder to block. The same environment looks different when the perceiver is better able to act than when actions are constrained. Claims of action's influence on spatial perception have been met with much controversy, and spurred many experiments designed to explore alternative explanations. In at least one case, these alternative explanations have failed to account for action's effect, thereby leading to the conclusion that the potential for action can truly influence spatial perception. The mystery remains, however, as to how action exerts its influence.

Introducing hat graphs.

Visualizing data through graphs can be an effective way to communicate one's results. A ubiquitous graph and common technique to communicate behavioral data is the bar graph. The bar graph was first invented in 1786 and little has changed in its format. Here, a replacement for the bar graph is proposed. The new format, called a hat graph, maintains some of the critical features of the bar graph such as its discrete elements, but eliminates redundancies that are problematic when the baseline is not at zero. Hat graphs also include design elements based on Gestalt principles of grouping and graph design principles. The effectiveness of the hat graph was tested in five empirical studies. Participants were nearly 40% faster to find and identify the condition that led to the biggest difference from baseline to final test when the data were plotted with hat graphs than with bar graphs. Participants were also more sensitive to the magnitude of an effect plotted with a hat graph compared with a bar graph that was restricted to having its baseline at zero. The recommendation is to use hat graphs when plotting data from discrete categories.

The perceptual experience of variability in line orientation is greatly exaggerated.

What is the perceptual experience of variability? Unconscious perceptual processes are well-calibrated to variability, as are unconscious motor processes, whereas cognitive processes are not well-calibrated and tend to underestimate variability. Regarding the perceptual experience of variability, perceivers are sensitive to differences in the variability of ensembles of objects, but any potential biases have not yet been explored. In the current experiments, participants viewed a set of lines at various orientations that were presented 1 at a time in a random order. Participants judged whether the orientations within each set were more similar to each other or more disperse. Although participants were sensitive to differences in spread, participants overestimated the variability of the set by 50%. The results have implications for mechanisms underlying ensemble perception, which is the extraction of summary statistics from a set of objects. In particular, there are both shared and unique processes related to perceiving similarities across objects (such as the mean orientation) and perceiving differences (such as their spread). Both visual abilities were thorough and used the full set of lines, rather than using only a subset, but the perception of spread relied more heavily on differences presented at the beginning whereas perception of the mean relied more heavily on features of the lines at the end of the animation. The results also have implications for visualizations of uncertainty, such as hurricane forecasts. A perceptual bias to overestimate variability could help counteract cognitive biases to underestimate variability. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

The uphill battle for action-specific perception.

The action-specific account of perception states that a perceiver's ability to act influences the perception of the environment. For example, participants tend to perceive distances as farther when presented up hills than on the flat ground. This tendency is known as the distance-on-hill effect. However, there is debate as to whether these types of effects are truly perceptual. Critics of the action-specific account of perception claim that the effects could be due to participants guessing the hypothesis and trying to comply with the experimental demands. The present study aims to explore the distance-on-hill effect and determine whether it is truly perceptual or whether past results were due to response bias. Participants judged the relative distance to targets on a hill and the flat ground. We found the distance-on-hill effect in virtual reality using a visual matching task. The distance-on-hill effect persisted even when participants were given explicit feedback about their estimates. We also found that the effect went away, as predicted by a perceptual explanation, when participants had to match the distance between two cones that were both on hills. These results offer important steps toward the painstaking task of determining whether action's effect on perception is truly perceptual.

In absence of an explicit judgment, action-specific effects still influence an action measure of perceived speed.

Action-specific effects, such as a fish appearing faster when it is harder to catch, have been primarily demonstrated using explicit perceptual judgments. These sorts of judgments rely on the cognitive or "what" visual pathway. An open question is whether action-specific effects also influence the action pathway. If fish look faster when the net is small, the net should be released earlier than when the net is big. Previously, this action measure was always paired with an explicit measure of fish speed, which is known to evoke the cognitive visual pathway. Here, net release time was examined without any explicit judgments. The action-specific effect of net size still emerged. Assuming net release time taps into the action pathway, the current studies provide support that action-specific effects occur within both the cognitive and action pathways, possibly because these effects operate on early visual processes prior to the split between the two pathways.

Is There a Chastity Belt on Perception?

Can one's ability to perform an action, such as hitting a softball, influence one's perception? According to the action-specific account, perception of spatial layout is influenced by the perceiver's abilities to perform an intended action. Alternative accounts posit that purported effects are instead due to nonperceptual processes, such as response bias. Despite much confirmatory research on both sides of the debate, researchers who promote a response-bias account have never used the Pong task, which has yielded one of the most robust action-specific effects. Conversely, researchers who promote a perceptual account have rarely used the opposition's preferred test for response bias, namely, the postexperiment survey. The current experiments rectified this. We found that even for people naive to the experiment's hypothesis, the ability to block a moving ball affected the ball's perceived speed. Moreover, when participants were explicitly told the hypothesis and instructed to resist the influence of their ability to block the ball, their ability still affected their perception of the ball's speed.