Publications

The low prevalence effect, which posits that people are more likely to miss a present target when its prevalence rate is low, has important implications for real-world scenarios such as cancer screening and bomb detection. This effect has primarily been studied under full visibility; however, real-world scenarios often come with incomplete visibility. Occlusion and poor visibility introduce perceptual uncertainty, potentially altering how people decide whether a target is present. Here, we applied Bayesian decision theory to a visual search paradigm with partial occlusion, examining how target prevalence (prior) and the degree of occlusion (likelihood information) affect search decisions. Participants made target present/absent responses to target/distractor stimuli. In Experiment 1, all items were invisible, forcing participants to rely on trial feedback to learn the target's prevalence. Experiment 2 also provided trial feedback, but allowed either a small or large portion of the display to be visible. Target prevalence varied between blocks (high, 50%; low, 25%). Results showed that, when items were entirely hidden, participants learned to probability match the target's prevalence. However, when some items were visible, participants rarely responded present when the target was in the occluded region. Comparing the data with models (e.g., probability matching, Bayesian maximizing) revealed mixed strategies. This study introduces a novel method for investigating visual search under occlusion and suggests that, although people integrate prevalence and sensory input, their decisions are not fully Bayesian.

Cortically induced blindness (CB) resulting from stroke damage to the early visual cortex leads to extensive, typically extrafoveal visual deficits and is known to alter large-scale oculomotor behavior. Here, we show that even with preserved foveal acuity, fixational oculomotor behavior is subtly altered in CB patients. Using high-precision eye tracking, we observed a small but consistent gaze offset toward the blind field during passive fixation, which disappeared during a high-acuity central task. Despite this offset, fixation precision in both tasks was comparable, and it was similar between CB patients and age-matched controls. Curiously, the underlying oculomotor dynamics were also similar across the two task conditions: Microsaccades exhibited nonsignificant directional tendencies, while ocular drift was biased away from the blind field. Our findings indicate that the adult oculomotor system dynamically adapts to asymmetric visual injury and/or input. We speculate that the small fixational offsets observed in CB may reflect an attentional pointer toward the blind field and/or a compensatory oculomotor rebalancing that counteracts an asymmetric visual drive following cortical damage. Together, these results reveal a surprising preservation of context-dependent fixation control following early visual cortex damage in adulthood.

Nature-based interventions (NBIs) present a promising but underexplored approach in recreational therapy for improving the quality of life in individuals with eating disorders (EDs). Due to limited research, this scoping review focuses on strategies and techniques for implementing NBIs, including wilderness therapy, horticultural therapy, forest bathing, and adventure therapy. Based on theoretical frameworks such as the Biophilia Hypothesis, Attention Restoration Theory, and Stress Reduction Theory, this review suggests ways nature-based experiences may promote emotional regulation, mindfulness, self-efficacy, and social well-being. However, several practical and individual challenges must be addressed, including limited access to natural spaces, financial and logistical constraints, psychological resistance, and the need for culturally sensitive approaches. Additionally, the lack of standardized evaluation methods makes it difficult to measure the effectiveness of NBIs in ED recovery. Given these challenges, this paper offers recommendations for recreational therapists to adapt and integrate NBIs into treatment, emphasizing creative solutions and individualized approaches. By exploring the possibilities of NBI with people who have EDs, this paper contributes to the growing conversation on using nature-based strategies to enhance therapeutic outcomes.

Blue care, a therapeutic approach utilizing natural aquatic environments, has emerged as a promising nature-based intervention (NBI) to enhance well-being. This literature review explored the concept of blue care as well as its relevance to recreational therapy (RT) practices. Supported by Ulrich's Stress Reduction Theory, this review discusses the restorative effects of water that support physical, emotional, and psychological health. Studies demonstrated that proximity to and engagement with blue spaces was associated with increased physical activity, improved mood, reduced symptoms of anxiety and depression, enhanced body image, and greater life satisfaction. These benefits were observed across diverse populations including children, older adults, and veterans. Interventions ranged from direct immersion activities, such as swimming and surfing, to passive methods, such as viewing aquatic environments or practicing guided imagery.

Recreational therapists work in a broad field with numerous service settings for individuals with disabilities. Students' learning may be enhanced by providing opportunities during class time to implement services for more unfamiliar populations. Therefore, the purpose of this study was to investigate students' reflections from a class time fieldwork experience (CTFE) in a recreational therapy (RT) class with adolescents who engage in health-risk behaviors. A retrospective, qualitative content analysis of 111 RT students' perspectives was used for this study, and two main themes emerged: exposure to an unfamiliar community population and identifying personal biases and judgments. Implications are identified for RT educators and practitioners to apply these findings to future CTFEs, internships, and employment opportunities.

PURPOSE: The purpose of this study was to investigate the morphological and hemodynamic characteristics of the ophthalmic artery (OA) in ocular ischemic syndrome (OIS) and identify features potentially associated with disease pathogenesis.

METHODS: This retrospective case-control study included 33 patients with OIS, 22 patients with internal carotid artery stenosis (ICAS), and 29 healthy controls. Clinical data and ophthalmic examinations were collected. The morphology and hemodynamics of the OA were quantified using three-dimensional (3D) reconstruction and computational fluid dynamics (CFD). Particle image velocimetry provided a qualitative consistency check for the CFD results.

RESULTS: The OA diameter in the OIS group was significantly smaller than that in the control and ICAS groups. Compared with the control group, the OIS group showed lower blood flow velocity and wall shear stress (8.25 ± 5.34 Pa vs. 13.50 ± 6.24 Pa; P = 0.004) at the OA origin. A smaller OA diameter and lower wall shear stress at the OA origin were significantly associated with the presence of OIS. A low wall shear stress was observed at the OA origin regardless of the flow direction in the OIS. Patients with high-velocity retrograde OA flow present severe ocular ischemic manifestations.

CONCLUSIONS: Low wall shear stress may be a consistent hemodynamic characteristic of eyes with OIS. This hemodynamic feature may induce inward remodeling of the OA, leading to further luminal narrowing and exacerbation of ocular ischemia. The presence of high-velocity retrograde OA flow may indicate a severe degree of ocular ischemia, highlighting the potential of OA hemodynamics for improving risk stratification and guiding management.

Density information is a possible primitive for the perception of numerosity. It has been argued, however, that the perception of numerosity is more precise than density perception at low numbers, whereas density is more precise for high numbers. An interpretive problem with the stimuli used to make those claims is that actual stimulus density was often mis-specified owing to an ambiguity regarding the idealized versus actual filled area. This ambiguity had the effect of underestimating density precision at low numerosities. Here we used a novel method of stimulus generation that allows us to accurately specify stimulus density independent of patch size and number, while varying patch size from trial to trial to dissociate numerosity and density. For both numerosity discrimination and density discrimination, we presented single stimuli in central vision for comparison with an internal standard. Feedback was given after each judgment. Using well-defined densities, density discrimination was more precise than numerosity perception at all densities and showed no evidence of varying as a function of density, as previously hypothesized. This was found with 8 practiced observers, and then replicated in a pre-registered study with 32 observers. As expected, feedback nullified size biases on number judgments, showing that observers were adaptively combining density and size. Reanalysis of data from a recent investigation of downward sloping Weber fractions for numerosity showed that the square root-like effects in those sorts of studies were most likely owing to reductions in patch size variance that were correlated with increases in density.

How stimulus properties are processed in the human brain over time is critical to how we engage in dynamic everyday environments. To understand how changes in basic stimulus properties relate to changes in human electrical brain activity over time, previous work has estimated the brain's temporal response function (TRF) by cross-correlating random luminance sequences with electroencephalogram (EEG) signals at various lags to approximate the brain's response to temporal changes in luminance. Using this technique, it was found that luminance changes produce long-lasting "echoes" in the alpha frequency range. However, the neural origin of these echoes and the precise stimulus features that induce them have not been extensively studied. We measured TRFs in response to luminance and contrast changes. Additionally, the fact that EEG responses generated in the primary visual cortex (V1) have a unique pattern of polarity reversal depending on the visual field location (with upper stimuli projecting negatively and lower projecting positively) allowed us to test whether the TRFs generated from upper or lower visual field stimulation were counter-phased, as would be expected if the echoes were generated within V1. We found a luminance echo lasting ∼1 s in the alpha frequency and contrast echoes lasting only around 300 ms. For both stimuli, the TRF was initially counter-phased between upper and lower visual fields but quickly became in phase after ∼100 ms. Our findings demonstrate the existence of contrast (in addition to luminance) echoes in the alpha band, which appear to emerge from V1, perhaps as a traveling wave.

PURPOSE: To evaluate the 1-year progression of retinal capillary nonperfusion in eyes with mild to severe nonproliferative diabetic retinopathy (NPDR) using noninvasive retinal imaging.

METHODS: The CHART study (Clinicaltrials.gov: NCT04636307) is a multicenter, observational, longitudinal study involving five European research centers and included 202 eyes from 155 participants with type 2 diabetes and mild to severe NPDR. Participants underwent comprehensive ophthalmologic examinations at baseline and 3, 6, and 12 months, including best-corrected visual acuity, color fundus photography (Early Treatment Diabetic Retinopathy Study [ETDRS] severity scale), optical coherence tomography (OCT), and OCT angiography (OCTA). Disease progression was evaluated using mixed-effects models.

RESULTS: Of the 202 eyes, 81 eyes were graded as ETDRS level 35, 63 eyes as level 43, 46 eyes as level 47, and 12 eyes as level 53. At baseline, significant differences were observed in OCTA metrics between diabetic retinopathy severity groups. A total of 169 eyes (84%) completed the 1-year follow-up. Over 1 year, eyes with ETDRS levels 35 and 43 showed significant increases in capillary nonperfusion, identified by decreases in skeletonized vessel density in the superficial capillary plexus (rates of progression: β = -0.217 mm-1/y, P = 0.006 and β = -0.310 mm-1/y, P = 0.002, respectively). Eyes with level 47 showed only a borderline statistically significant decrease (P = 0.074), while eyes with level 53 remained stable. Microaneurysm turnover (MAT), formation, and disappearance rates increased in more severe NPDR stages (levels 47 and 53).

CONCLUSIONS: Retinal capillary nonperfusion progresses significantly over 1 year in mild to moderate NPDR, identified by changes in rates of progression of vessel and perfusion densities. In more severe stages (levels 47 and 53), capillary nonperfusion stabilizes, and a hyperperfusion response is identified by increases in MAT associated with the development of intraretinal microvascular abnormalities.

TRANSLATIONAL RELEVANCE: This study provides quantitative data on 1-year progression of retinal capillary nonperfusion in NPDR using noninvasive imaging, offering the basis for future interventional trials.