When we use our hands to estimate the length of a stick in the Müller-Lyer illusion, we are highly susceptible to the illusion. But when we prepare to act on sticks under the same conditions, we are significantly less susceptible. Here, we asked whether people are susceptible to illusion when they use their hands not to act on objects but to describe them in spontaneous co-speech gestures or conventional sign languages of the deaf. Thirty-two English speakers and 13 American Sign Language signers used their hands to act on, estimate the length of, and describe sticks eliciting the Müller-Lyer illusion. For both gesture and sign, the magnitude of illusion in the description task was smaller than the magnitude of illusion in the estimation task and not different from the magnitude of illusion in the action task. The mechanisms responsible for producing gesture in speech and sign thus appear to operate not on percepts involved in estimation but on percepts derived from the way we act on objects.
Jealousy may have evolved to protect valuable social bonds from interlopers, but some researchers have suggested that it is linked to self-awareness and theory of mind, leading to claims that it is unique to humans. We presented dogs ( N = 18; 11 females; age: M = 4.6 years, SD = 1.9) with situations in which they could observe an out-of-sight social interaction between their owner and a fake dog or between their owner and a fleece cylinder. We found evidence for three signatures of jealous behavior in dogs: (a) Jealousy emerged only when the dog’s owner interacted with a perceived social rival, (b) it occurred as a consequence of that interaction and not because of the mere presence of a conspecific, and (c) it emerged even for an out-of-sight interaction between the dog’s owner and a social rival. These results support claims that dogs display jealous behavior, and they provide the first evidence that dogs can mentally represent jealousy-inducing social interactions.
We applaud the forward-looking nature of the Commentary provided by Kragel et al. (2021) on our article, “What Is the Test-Retest Reliability of Common Task-Functional MRI Measures? New Empirical Evidence and a MetaAnalysis” (Elliott et al., 2020). We fully agree with their emphasis on the importance of avoiding overgeneralization when considering measurement reliability in taskfunctional MRI (task-fMRI). Because no single reliability estimate can capture the multitude of possible task-fMRI measures, statements such as “every brain activity study you’ve ever read is wrong” (Cohen, 2020) are misleading and unnecessarily undermine our joint efforts to improve task-fMRI. In fact, that is why we addressed this very point in our article (see p. 801). Nevertheless, we take this opportunity to clarify three subtle but meaningful ways that our perspective diverges from that promoted by Kragel et al. in their Commentary. First, as we embrace the future, we must also account for and build on the past while being realistic about the state of the present. Kragel et al. point out the exciting potential of “multivariate measures optimized using machine learning” that they claim are “commonly used for biomarker discovery” (p. 622). While we agree that multivariate measures are becoming more widespread and should continue to be developed and explored (see p. 802 of our original article), such measures are still far from being universal in task-fMRI biomarker research. Because psychological science is a cumulative enterprise, criticism and honest assessment of the current state of the science are essential to the continued advancement of the field. In this vein, we surveyed the reliability of region-of-interest-based task-fMRI activation, which is one of the most commonly adopted measures reported in the literature over the past 2 decades. Our meta-analysis directly provided evidence for this continued use, as approximately half of the reliability estimates we found had been published in the previous 5 years. These measures are not relics of the past; they are in common use today and still frequently incorporated as primary measures in largescale, state-of-the-art imaging efforts focused on biomarker development and individual-differences research. For example, the Human Connectome Project, UK Biobank, and the Adolescent Brain Cognitive Development study all have incorporated fMRI tasks designed to activate particular brain areas and circuits (Casey et al., 2018; Miller et al., 2016; Van Essen et al., 2013). These are large-scale, expensive projects creating MRI data sets for future neuroscience research. Thus, the poor reliability reported in our article is critical for not only past but also present biomarker research using traditional task-fMRI activation. We hope that by reevaluating standard practices in light of the reliability limitations detailed in our article, we can guard against repeating and perpetuating these limitations in such future research. Second, we would like to highlight an important distinction between the main aim of our article and several of the examples offered by Kragel et al. in their Commentary. The central concern addressed in our article was whether commonly used measures of task-fMRI activation are reliable enough for individual-differences research and brain biomarkers. To answer this question, 996665 PSSXXX10.1177/0956797621996665Elliott et al.Psychometric Theory in Neuroscience research-article2021
Past work has suggested that people prescribe optimism—believing it is better to be optimistic, instead of accurate or pessimistic, about uncertain future events. Here, we identified and addressed an important ambiguity about whether those findings reflect an endorsement of biased beliefs—that is, whether people prescribe likelihood estimates that reflect overoptimism. In three studies, participants ( N = 663 U.S. university students) read scenarios about protagonists facing uncertain events with a desired outcome. Results replicated prescriptions of optimism when we used the same solicitations as in past work. However, we found quite different prescriptions when using alternative solicitations that asked about potential bias in likelihood estimations and that did not involve vague terms such as “optimistic.” Participants generally prescribed being optimistic, feeling optimistic, and even thinking optimistically about the events, but they did not prescribe overestimating the likelihood of those events.
Because the motions of everyday objects obey Newtonian mechanics, perhaps these laws or approximations thereof are internalized by the brain to facilitate motion perception. Shepard’s seminal investigations of this hypothesis demonstrated that the visual system fills in missing information in a manner consistent with kinematic constraints. Here, we show that perception relies on internalized regularities not only when filling in missing information but also when available motion information is inconsistent with the expected outcome of a physical event. When healthy adult participants ( Ns = 11, 11, 12, respectively, in Experiments 1, 2, and 3) viewed 3D billiard-ball collisions demonstrating varying degrees of consistency with Newtonian mechanics, their perceptual judgments of postcollision trajectories were biased toward the Newtonian outcome. These results were consistent with a maximum-likelihood model of sensory integration in which perceived target motion following a collision is a reliability-weighted average of a sensory estimate and an internal prediction consistent with Newtonian mechanics.
Whom do individuals blame for intergroup conflict? Do people attribute responsibility for intergroup conflict to the in-group or the out-group? Theoretically integrating the literatures on intergroup relations, moral psychology, and judgment and decision-making, we propose that unpacking a group by explicitly describing it in terms of its constituent subgroups increases perceived support for the view that the unpacked group shoulders more of the blame for intergroup conflict. Five preregistered experiments ( N = 3,335 adults) found support for this novel hypothesis across three distinct intergroup conflicts: the Israeli-Palestinian conflict, current racial tensions between White people and Black people in the United States, and the gender gap in wages in the United States. Our findings (a) highlight the independent roles that entrenched social identities and cognitive, presentation-based processes play in shaping blame judgments, (b) demonstrate that the effect of unpacking groups generalizes across partisans and nonpartisans, and (c) illustrate how constructing packed versus unpacked sets of potential perpetrators can critically shape where the blame lies.
More than 100 countries allow people to vote directly on policies in direct democracy elections (e.g., 2016 Brexit referendum). Politicians are often responsible for writing ballot language, and voters frequently encounter ballot measures that are difficult to understand. We examined whether eye movements from a small group of individuals can predict the consequences of ballot language on large-scale voting decisions. Across two preregistered studies (Study 1: N = 120 registered voters, Study 2: N = 120 registered voters), we monitored laboratory participants’ eye movements as they read real ballot measures. We found that eye-movement responses associated with difficulties in language comprehension predicted aggregate voting decisions to abstain from voting and vote against ballot measures in U.S. elections (total number of votes cast = 137,661,232). Eye movements predicted voting decisions beyond what was accounted for by widely used measures of language difficulty. This finding demonstrates a new way of linking eye movements to out-of-sample aggregate-level behaviors.
Brain damage or disruption to the primary visual cortex sometimes produces blindsight, a striking condition in which patients lose the ability to consciously detect visual information yet retain the ability to discriminate some attributes without awareness. Although there have been few demonstrations of somatosensory equivalents of blindsight, the lesions that produce "numbsense," in which patients can make accurate guesses about tactile information without awareness, have been rare and localized to different regions of the brain. Despite transient loss of tactile awareness in the contralateral hand after transcranial magnetic stimulation (TMS) of the primary somatosensory cortex but not TMS of a control site, 12 participants (six female) reliably performed at above-chance levels on a localization task. These results demonstrating TMS-induced numbsense implicate a parallel somatosensory pathway that processes the location of touch in the absence of awareness and highlight the importance of primary sensory cortices for conscious perception.
A primary challenge for alibi-generation research is establishing the ground truth of real-world events of interest. In the current study, we used a smartphone app to record data on adult participants ( N = 51) for a month prior to a memory test. The app captured accelerometry data, GPS locations, and audio environments every 10 min. After a week-long retention interval, we asked participants to identify where they were at a given time from among four alternatives. Participants were incorrect 36% of the time. Furthermore, our forced-choice procedure allowed us to conduct a conditional logit analysis to assess the different aspects of the events that the participants experienced and their relative importance to the decision process. We found strong evidence that participants confuse days across weeks. In addition, people often confused weeks in general and also hours across days. Similarity of location induced more errors than similarity of audio environments or movement types.
= 1,490), participants were asked to imagine themselves as programmers of self-driving cars who had to decide how to program the car to respond in a potential accident: spare the driver or spare pedestrians. Alternatively, participants imagined that they were a mayor grappling with difficult moral dilemmas concerning COVID-19. Either they, themselves, had to decide how to program the car or which COVID-19 policy to implement (high-agency condition) or they were told by their superior how to act (low-agency condition). After learning that a tragic outcome occurred because of their action, participants reported their felt culpability. Although we expected people to feel less culpable about the outcome if they acted in accordance with their superior's injunction than if they made the decision themselves, participants actually felt more culpable when they followed their superior's order. Some possible reasons for this counterintuitive finding are discussed.