Nevin Manimala

J Vis. 2025 Apr 1;25(5):9. doi: 10.1167/jov.25.5.9.

ABSTRACT

Fixational eye movements (FEMs) are small, fluctuating eye motions when fixating on a target. Given our visual system is evolved, we may ask why FEMs are beneficial and whether they are optimal. A possible reason for FEMs is overcoming retinal adaptation (fading perception of a fixed image). We present a simple model system allowing theoretical investigation of FEM influence on information about an external stimulus. The model incorporates temporal stimulus modulation, retinal image motion due to the drift component of FEMs, blurring due to optics and receptor size, uniform sampling by the receptor array, adaptation via a bandpass temporal filter, and added noise. We investigate how elements of the model mediate the information transmitted, via: i) mutual information between visual system response and external stimulus, ii) direct estimation of stimulus from the system response, and iii) contrast threshold for signal detection. For all these we find a common quantity that must be maximized. For each spatial frequency this quantity is a summed power transmitted due to stimulus temporal modulation and phase shifts from FEMs, when passed through the temporal filter. We demonstrate that the information transmitted can be increased by adding local persistence to an underlying diffusive process. We also quantify the contribution of FEMs to signal detection for targets of different size and duration; such predictions provide a qualitative account of human psychophysical performance.

PMID:40215060 | DOI:10.1167/jov.25.5.9

J Vis. 2025 Apr 1;25(5):35. doi: 10.1167/jov.25.5.35.

ABSTRACT

It has been proposed that colour perception is calibrated to the chromatic statistics of the environment. Here we investigate whether perceived white is calibrated to the chromatic statistics of the local current ‘visual diet’. We compare achromatic settings for participants in Norway living above (Tromsø, N = 165) or below (Oslo, N = 158) the Arctic Circle and across seasons. To capture the local visual diets we used images from colour-calibrated head-mounted cameras worn during daily life. For each image we computed average chromaticity (L/(L+M) and S/(L+M)) and the amount of blue-yellow bias in the distribution of chromaticities. We find that perceived white is warmer (higher L/(L+M) and lower S/(L+M)), and more blue-yellow biased for observers living in Oslo compared to Tromsø. However, visual diets were warmer and more blue-yellow biased in Tromsø compared to Oslo. Perceived white did not vary significantly with season, yet visual diets were warmest in the winter. In order to explore the effects of visual environment in early life, we also investigate how perceived white varies with latitude of birth and season of birth for participants living in Tromsø. Perceived white was lower in S/(L+M) (yellower) for adults born below the Arctic Circle than adults born above, and was higher in L/(L+M) (redder) for adults born in the summer. Combined, the findings suggest a possible link between colour perception and visual diet, and we discuss potential mechanisms.

PMID:40215034 | DOI:10.1167/jov.25.5.35

J Vis. 2025 Apr 1;25(5):38. doi: 10.1167/jov.25.5.38.

ABSTRACT

It has been suggested that objects are more likely to be warmer in colour, redder and more saturated than the background. Here, we investigate the colour statistics of objects, and the brain regions that are responsive to these statistics. First, we analysed the Natural Scenes Dataset (NSD), a 7T dataset in which 8 participants viewed up to 10,000 natural scenes. Our analysis of the chromaticities of the 80 segmented object classes and backgrounds confirmed that object pixels were warmer, redder, more saturated and darker than background pixels. The probability that pixels were from objects rather than backgrounds (the ‘Object Colour Probability’, OCP) was calculated for 240 hue bins. The mean OCP of images correlated with NSD BOLD responses mostly in the ventral visual pathway. Other image statistics (e.g., number of food pixels) better explained the responses of correlated voxels. A second fMRI study, in which colours were shown as a single patch on a grey background, was analysed to study whether ventral visual pathway is responsive to OCP in the absence of other scene statistics. To constrain our analyses to functionally relevant areas, we used independent functional localizers to identify colour- and object-selective areas and combined these with NSD defined OCP responsive areas. The OCP of the colour patches significantly correlated with BOLD in colour-selective but not object-selective visual regions. Implications for the role of colour in object vision are discussed.

PMID:40215031 | DOI:10.1167/jov.25.5.38

J Vis. 2025 Apr 1;25(5):41. doi: 10.1167/jov.25.5.41.

ABSTRACT

Visual discomfort describes an aversive subjective experience characterised by perceptual distortions, blurred vision, diplopia, pain in the eyes, headache and/or nausea. Previous laboratory studies have found that levels of visual discomfort can be predicted from some statistical properties of scenes, including the spectral slope (e.g. Penacchio & Wilkins, 2015) and colour contrast (Juricevic et al. 2010; Penacchio et al. 2021). Lighting flicker (e.g. Yoshimoto et al., 2017) and colour temperature (e.g. Kakitsuba 2015) have also been shown to trigger discomfort. We investigated everyday occurrences of visual discomfort using a visual survey method. Participants (N = 36) captured scenes which they found to be visually uncomfortable within a university library. Participants gave a narrative and discomfort rating for each image. We also surveyed the lighting in the photographed areas, measuring flicker and the spectral power distribution of the illumination. Analysis showed some support for the importance of the image statistical features identified in laboratory studies, although there was no interaction between these features and lighting flicker or colour temperature. Qualitative analysis of participant narratives revealed that experiences of discomfort were attributed to low-level features (e.g. pattern, contrast), but also structural features (e.g. depth, disorganisation). These results provide new insights into the causes of visual discomfort in the everyday environment.

PMID:40215028 | DOI:10.1167/jov.25.5.41

J Vis. 2025 Apr 1;25(5):43. doi: 10.1167/jov.25.5.43.

ABSTRACT

Stable visual ensemble statistics can support performance on a visual search task (e.g. Corbett and Melcher, 2014). Such results may indicate improvements in the efficiency of visual cognition in response to a more predictable environment. Observations of improved cognition when immersed in nature (e.g. Berman et al., 2008) have been related to concepts of perceptual fluency and Attention Restoration. We investigated whether the statistical stability of natural scenes could be the underlying mechanism supporting enhancements in visual cognition related to natural images. In experiment 1, we replicated the first study from Corbett and Melcher (2014), showing that sequences of trials with a stable mean size of Gabor elements results in enhanced visual search for an orientation singleton target, compared to sequences with an unstable mean size. In experiment 2, we embedded visual search targets within a set of natural scene images. We leveraged existing variation in the image statistics between images to present sequences where the slope of the Fourier amplitude spectrum was relatively stable (gradually increasing/decreasing) or unstable (randomly ordered). The results have implications for our understanding of the effect of the visual environment on visuo-cognitive functions and the extraction of image statistics by the visual system. We discuss the likely role for eye movements in sampling natural scenes.

PMID:40215026 | DOI:10.1167/jov.25.5.43

J Vis. 2025 Apr 1;25(5):54. doi: 10.1167/jov.25.5.54.

ABSTRACT

Exposure to the colour statistics of natural scenes can both induce and counteract individual differences in colour perception. If different people inhabit different chromatic environments, calibration of the visual system to the colour statistics of those environments can cause individual differences in colour perception. Conversely, exposure to common colour statistics in a common visual environment can reduce individual differences in colour perception that would otherwise be caused by individual differences in physiological factors such as macular pigment density, lens density and cone spectral sensitivities. I will present some examples of our research on these themes, including a cross-environmental study on colour perception between participants living in remote rural versus urban environments in Ecuador (Skelton et al. 2023, Proc. Roy. Soc. B), and studies that explore how the visual systems of anomalous trichromats compensate for their altered cone spectral sensitivities.

PMID:40215015 | DOI:10.1167/jov.25.5.54

J Vis. 2025 Apr 1;25(5):57. doi: 10.1167/jov.25.5.57.

ABSTRACT

Infants start to interact with their visual environment during the first postnatal months. Immaturities in gross motor responses and spatial vision constrain their visual behavior during this rapid development. Analyses of first-person video and eye-tracking data from infants were performed to understand key components of visual experience during this period of visual learning.

METHODS: Infants wore head-mounted scene and binocular eye-tracking cameras (modified Pupil Labs Core) while engaging in naturalistic behavior in an 8ftx8ft home-like environment. Calibrated eye movements were identified using standard approaches (e.g. Engbert & Mergenthaler, 2006) and image statistics were extracted at fixation locations (>200ms).

RESULTS: Recordings (10.5 hours) at ages 2-3 (n=24) 5-6 (35) 8-9 (27) & 11-12 (11) months were analyzed. Eye position and saccade amplitude distributions relative to the head were tighter for younger infants. The distribution of RMS contrast around fixation was also highest at younger ages.

CONCLUSIONS: The youngest infants with limited head and trunk control exhibited the most restricted range of eye movements, suggesting no gaze shift compensation for limited mobility. This likely leads to less active sampling of the scene, slower rates of change in input, and a tight link between head- and eye-centered frames of reference. Early experience also provides a concentration of contrast serving the development of foveal and parafoveal function.

PMID:40215012 | DOI:10.1167/jov.25.5.57

Psychooncology. 2025 Apr;34(4):e70146. doi: 10.1002/pon.70146.

ABSTRACT

OBJECTIVE: To identify the contribution of psychosocial characteristics, supportive care needs, or quality of life on breast cancer survival outcomes.

METHODS: This study used data from a population-based longitudinal study involving women diagnosed with invasive breast cancer (n = 3326, response rate = 71%) in Queensland, Australia, 2010-2013, and followed up to 2020. Flexible parametric survival models were used to identify which factors were associated with survival outcomes. Model fit was assessed using D and $R_D^2$ statistics.

RESULTS: Unmet physical and daily living needs, social support, age, stage at diagnosis, tumour grade, clinical subtype and mode of detection explained 39% of survival variability ( $R_D^2$ 0.39; 95% CI 0.33-0.44), with a Harrell’s C statistic of 0.84 (95% CI 0.81-0.86). Unmet physical and daily living needs and social support, which fall under the categories of supportive care needs and psychosocial characteristics respectively, were identified as key factors that predict breast cancer survival, explaining 3% of survival variability. When compared to women who had less unmet physical needs and adequate social support (5-year survival: 96.6%, 95% CI 92%-99%), those who had more unmet physical needs and limited social support had poorer breast cancer-specific survival (5-year survival: 86.8%, 95% CI 72%-95%).

CONCLUSION: The study found that unmet physical and daily living needs and social support play a marginal but significant role in influencing breast cancer outcomes. The findings enhance the current literature regarding the impact of psychosocial characteristics and supportive care needs on breast cancer survival and suggest that integrating psychosocial support and interventions alongside medical treatment may further improve the survival outcomes for women diagnosed with breast cancer.

PMID:40215001 | DOI:10.1002/pon.70146

Pediatr Blood Cancer. 2025 Apr 11:e31700. doi: 10.1002/pbc.31700. Online ahead of print.

ABSTRACT

BACKGROUND: Children with cancer face an increased risk of complications and death beyond the 5-year survival mark. National surveillance efforts facilitate the systematic tracking of long-term health outcomes, including treatment-related complications and late mortality, among childhood cancer survivors. We aimed to describe the population of 5-year childhood cancer survivors in Canada, quantify the risk of death among survivors relative to the general population, and identify characteristics associated with late mortality.

METHODS: This retrospective cohort study used the Canadian Cancer Registry linked to the Canadian Vital Statistics-Death database (excludes Quebec). Survivors were diagnosed with cancer before 15 years old (1992-2012) and still alive five years after diagnosis. We approximated the risk of late mortality relative to the general population using standardized mortality ratios (SMRs) and absolute excess ratios (AERs). Cumulative all-cause and cause-specific mortality and time-to-event models identified characteristics associated with late mortality.

RESULTS: Of the 10,800 5-year survivors, 405 (4%) had a late death by 2017 (median follow-up: 9.1 years). Cancer recurrence or progression caused most late deaths (64%), followed by subsequent primary neoplasms (11%) and other health-related causes (15%). Survivors had a higher risk of all-cause mortality than the general population (SMR = 9.4; 95% CI = 8.5-10.4; AER = 34.8, 95% CI = 30.8-38.8). Risk was highest in the first 5-9 years of follow-up. Cumulative mortality differed significantly by age at diagnosis, sex and cancer type.

INTERPRETATION: Our results underline the importance of long-term surveillance of childhood cancer survivors, as mortality rates remain higher than the general population for at least two decades after diagnosis.

PMID:40214998 | DOI:10.1002/pbc.31700

JAMA Netw Open. 2025 Apr 1;8(4):e254516. doi: 10.1001/jamanetworkopen.2025.4516.

ABSTRACT

IMPORTANCE: Following decades-long declines, significant increases in abortion rates have been reported in some jurisdictions from 2020 to 2023, but it is not yet known whether these trends are occurring in Canada.

OBJECTIVE: To assess abortion rates in Ontario from 2012 to 2022 and to examine trend changes associated with mifepristone availability, the COVID-19 pandemic, and postpandemic periods.

DESIGN, SETTING, AND PARTICIPANTS: This population-based interrupted time series cohort study examined all medication and procedural abortions provided in Ontario from January 1, 2012, to December 31, 2022, to females aged 15 to 44 years with provincial insurance coverage, identified using linked health administrative data that included records from practitioner billings, inpatient and outpatient hospital services, same-day surgeries, and outpatient prescription dispensations.

EXPOSURE: Availability of mifepristone regulated as a normal (ie, prescribed by an authorized prescriber without additional certification or registration and dispensed by a pharmacist) prescription medication (in November 2017) and the COVID-19 pandemic period (from March 2020 to December 2021).

MAIN OUTCOMES AND MEASURES: The main outcome was the abortion rate (number of abortions per 1000 females per year) overall and within age strata, using an interrupted time series design.

RESULTS: Of 422 867 medication and procedural abortions identified using data from health records of 225 540 reproductive-aged females (mean [SD] age, 28.5 [6.6] years), the abortion rate declined steadily from 15.6 abortions per year per 1000 females, aged 15 to 44 years, in 2012 to 12.3 in 2021 and then increased to 14.1 in 2022. When mifepristone was introduced in 2017 as a normal prescription medication, no immediate change in the abortion rate (-0.1 [95% CI, -0.7 to 0.8]) and a nonsignificant slope increase (0.6 [95% CI, -0.5 to 0.7]) were found. However, this trend resulted in an additional 1.5 (95% CI, 0.3-2.6) abortions per 1000 females by the first quarter of 2020 compared with premifepristone trends; rates increased more among those aged 15 to 19 years, less among those aged 35 to 44 years, and did not increase for those aged 25 to 29 years. During the pandemic period, abortion rates decreased by 1.2 (95% CI, -2.5 to -0.8), most pronounced among those aged 20 to 34 years. Compared with expected rates based on premifepristone trends, 5-year availability of normally prescribed mifepristone was associated with a rate difference of 1.9 (95% CI, 0.7-5.4) in 2022, with a greater increase among those aged 20 to 24 years (4.2 [95% CI, 1.5-9.0]) and no change among those aged 25 to 29 years (1.0 [95% CI, -1.7 to 6.2]). The increased abortion rate in 2022 was consistent with 5-year trends following normally prescribed mifepristone, although social forces potentially impacting international rates may have contributed.

CONCLUSIONS AND RELEVANCE: This study found that, following longstanding declines, abortion rates in Ontario gradually increased with mifepristone availability in 2017 in Ontario. Following a pandemic-related decrease in rates (in 2020 and 2021), substantial increases in abortion rates reported elsewhere from 2020 to 2023 did not occur in Ontario as of 2022, suggesting that Ontario’s health services environment and Canada’s regulatory and policy approach to preserving reproductive health services may have helped stabilize abortion rates. Future research is needed to understand how sociocultural changes affecting abortion service use elsewhere may be affecting contraception access and use and thus abortion rates in Canada.

PMID:40214991 | DOI:10.1001/jamanetworkopen.2025.4516