Effective Altruism as an Ethical Lens on Research Priorities

Effective altruism is an ethical framework for identifying the greatest potential benefits from investments. Here, we apply effective altruism concepts to maximize research benefits through identification of priority stakeholders, pathosystems, and research questions and technologies. Priority stakeholders for research benefits may include smallholder farmers who have not yet attained the minimal standards set out by the United Nations Sustainable Development Goals; these farmers would often have the most to gain from better crop disease management, if their management problems are tractable. In wildlands, prioritization has been based on the risk of extirpating keystone species, protecting ecosystem services, and preserving wild resources of importance to vulnerable people. Pathosystems may be prioritized based on yield and quality loss, and also factors such as whether other researchers would be unlikely to replace the research efforts if efforts were withdrawn, such as in the case of orphan crops and orphan pathosystems. Research products that help build sustainable and resilient systems can be particularly beneficial. The "value of information" from research can be evaluated in epidemic networks and landscapes, to identify priority locations for both benefits to individuals and to constrain regional epidemics. As decision-making becomes more consolidated and more networked in digital agricultural systems, the range of ethical considerations expands. Low-likelihood but high-damage scenarios such as generalist doomsday pathogens may be research priorities because of the extreme potential cost. Regional microbiomes constitute a commons, and avoiding the "tragedy of the microbiome commons" may depend on shifting research products from "common pool goods" to "public goods" or other categories. We provide suggestions for how individual researchers and funders may make altruism-driven research more effective.[Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Statistical modelling studies examining the dimensional structure of psychopathology experienced by adults with intellectual disabilities: Systematic review

Diagnosing mental ill-health using categorical classification systems has limited validity for clinical practice and research. Dimensions of psychopathology have greater validity than categorical diagnoses in the general population, but dimensional models have not had a significant impact on our understanding of mental ill-health and problem behaviours experienced by adults with intellectual disabilities. This paper systematically reviews the methods and findings from intellectual disabilities studies that use statistical methods to identify dimensions of psychopathology from data collected using structured assessments of psychopathology. The PRISMA framework for systematic review was used to identify studies for inclusion. Study methods were compared to best-practice guidelines on the use of exploratory factor analysis. Data from the 20 studies included suggest that it is possible to use statistical methods to model dimensions of psychopathology experienced by adults with intellectual disabilities. However, none of the studies used methods recommended for the analysis of non-continuous psychopathology data and all 20 studies used statistical methods that produce unstable results that lack reliability. Statistical modelling is a promising methodology to improve our understanding of mental ill-health experienced by adults with intellectual disabilities but future studies should use robust statistical methods to build on the existing evidence base.

Lower cardiorespiratory fitness contributes to increased insulin resistance and fasting glycaemia in middle-aged South Asian compared with European men living in the UK

AIMS/HYPOTHESIS

This study aimed to determine the extent to which increased insulin resistance and fasting glycaemia in South Asian men, compared with white European men, living in the UK, was due to lower cardiorespiratory fitness (maximal oxygen uptake [VO(2max)]) and physical activity.

METHODS

One hundred South Asian and 100 age- and BMI-matched European men without diagnosed diabetes, aged 40-70 years, had fasted blood taken for measurement of glucose concentration, HOMA-estimated insulin resistance (HOMA(IR)), plus other risk factors, and underwent assessment of physical activity (using accelerometry), VO(2max), body size and composition, and demographic and other lifestyle factors. For 13 South Asian and one European man, HbA1c levels were >6.5% (>48 mmol/mol), indicating potential undiagnosed diabetes; these men were excluded from the analyses. Linear regression models were used to determine the extent to which body size and composition, fitness and physical activity variables explained differences in HOMA(IR) and fasting glucose between South Asian and European men.

RESULTS

HOMA(IR) and fasting glucose were 67% (p < 0.001) and 3% (p < 0.018) higher, respectively, in South Asians than Europeans. Lower VO(2max), lower physical activity and greater total adiposity in South Asians individually explained 68% (95% CI 45%, 91%), 29% (11%, 46%) and 52% (30%, 80%), respectively, and together explained 83% (50%, 119%) (all p < 0.001) of the ethnic difference in HOMA(IR). Lower VO(2max) and greater total adiposity, respectively, explained 61% (9%, 111%) and 39% (9%, 76%) (combined effect 63% [8%, 115%]; all p < 0.05) of the ethnic difference in fasting glucose.

CONCLUSIONS/INTERPRETATION

Lower cardiorespiratory fitness is a key factor associated with the excess insulin resistance and fasting glycaemia in middle-aged South Asian, compared with European, men living in the UK.

Parent-infant vocalisations at 12 months predict psychopathology at 7 years

This study investigated the utility of adult and infant vocalisation in the prediction of child psychopathology. Families were sampled from the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. Vocalisation patterns were obtained from 180 videos (60 cases and 120 randomly selected sex-matched controls) of parent-infant interactions when infants were one year old. Cases were infants who had been subsequently diagnosed aged seven years, with at least one psychiatric diagnostic categorisation using the Development and Wellbeing Assessment. Psychopathologies included in the case group were disruptive behaviour disorders, oppositional-conduct disorders, Attention Deficit Hyperactivity Disorder, pervasive development disorder, and emotional disorders. Associations between infant and parent vocalisations and later psychiatric diagnoses were investigated. Low frequencies of maternal vocalisation predicted later development of infant psychopathology. A reduction of five vocalisations per minute predicted a 44% (95%CI: 11-94%; p-value=0.006) increase in the odds of an infant being a case. No association was observed between infant vocalisations and overall case status. In sum, altered vocalisation frequency in mother-infant interactions at one year is a potential risk marker for later diagnosis of a range of child psychopathologies.

Regulation of synaptic connections in the rabbit ciliary ganglion

One of the intriguing questions about the establishment of synaptic connections is how appropriate numbers of different axons come to innervate each target neuron. A reorganization of connections in early postnatal life appears to be an important aspect of this process, since many of the axons terminals that initially innervate target cells are subsequently lost. The rabbit ciliary ganglion is a remarkably simple neural ensemble in which to examine this rearrangement of developing synaptic connections. Using this system we have found that a reduction in the number of axons innervating each cell occurs without any change in the number of ciliary ganglion cells or preganglionic neurons; therefore the rearrangement is not based on cell death. The number of different axons that ultimately innervate each cell is, however, influenced in some way by the geometry of individual target neurons. Thus, mature ganglion cells that lack dendrites are generally innervated by a single axon, while neurons with increasingly complex dendritic arbors receive innervation from a commensurate number of different axons. At birth, on the other hand, neurons with or without dendritic processes receive about the same number of preganglionic inputs. These results suggest that the geometry of the target cell influences the competitive interaction between different axons innervating the same neuron. Indeed, an important function of dendrites may be to regulate the number of axons that innervate each nerve cell.

An empirical explanation of the Chubb illusion

The perceived difference in brightness between elements of a patterned target is diminished when the target is embedded in a similar surround of higher luminance contrast (the Chubb illusion). Here we show that this puzzling effect can be explained by the degree to which imperfect transmittance is likely to have affected the light that reaches the eye. These observations indicate that this 'illusion' is yet another signature of the fundamentally empirical strategy of visual perception, in this case generated by the typical influence of transmittance on inherently ambiguous stimuli.

A wholly empirical explanation of perceived motion

Because the retinal activity generated by a moving object cannot specify which of an infinite number of possible physical displacements underlies the stimulus, its real-world cause is necessarily uncertain. How, then, do observers respond successfully to sequences of images whose provenance is ambiguous? Here we explore the hypothesis that the visual system solves this problem by a probabilistic strategy in which perceived motion is generated entirely according to the relative frequency of occurrence of the physical sources of the stimulus. The merits of this concept were tested by comparing the directions and speeds of moving lines reported by subjects to the values determined by the probability distribution of all the possible physical displacements underlying the stimulus. The velocities reported by observers in a variety of stimulus contexts can be accounted for in this way.

Why we see things the way we do: evidence for a wholly empirical strategy of vision

Many otherwise puzzling aspects of the way we see brightness, colour, orientation and motion can be understood in wholly empirical terms. The evidence reviewed here leads to the conclusion that visual percepts are based on patterns of reflex neural activity shaped entirely by the past success (or failure) of visually guided behaviour in response to the same or a similar retinal stimulus. As a result, the images we see accord with what the sources of the stimuli have typically turned out to be, rather than with the physical properties of the relevant objects. If vision does indeed depend upon this operational strategy to generate optimally useful perceptions of inevitably ambiguous stimuli, then the underlying neurobiological processes will eventually need to be understood within this conceptual framework.

The relevance of visual perception to cortical evolution and development

The quality of brightness--perhaps the simplest visual attribute we perceive--appears to be determined probabilistically. In this empirical conception of the perception of light, the stimulus-induced activity of visual cortical neurons does not encode the retinal image or the properties of the stimulus per se, but associations (percepts) determined by the relative probabilities of the possible sources of the stimulus. If this theory is correct, the rationale for the prolonged postnatal construction of visual circuitry--and the evolution of this visual scheme--is to strengthen and/or create by activity-dependent feedback the empirically determined association on which vision depends.

An empirical explanation of color contrast

For reasons not well understood, the color of a surface can appear quite different when placed in different chromatic surrounds. Here we explore the possibility that these color contrast effects are generated according to what the same or similar stimuli have turned out to signify in the past about the physical relationships between reflectance, illumination, and the spectral returns they produce. This hypothesis was evaluated by (i) comparing the physical relationships of reflectances, illuminants, and spectral returns with the perceptual phenomenology of color contrast and (ii) testing whether perceptions of color contrast are predictably changed by altering the probabilities of the possible sources of the stimulus. The results we describe are consistent with a wholly empirical explanation of color contrast effects.

Why are angles misperceived?

Although it has long been apparent that observers tend to overestimate the magnitude of acute angles and underestimate obtuse ones, there is no consensus about why such distortions are seen. Geometrical modeling combined with psychophysical testing of human subjects indicates that these misperceptions are the result of an empirical strategy that resolves the inherent ambiguity of angular stimuli by generating percepts of the past significance of the stimulus rather than the geometry of its retinal projection.

Color vision and the four-color-map problem

Four different colors are needed to make maps that avoid adjacent countries of the same color. Because the retinal image is two dimensional, like a map, four dimensions of chromatic experience would also be needed to optimally distinguish regions returning spectrally different light to the eye. We therefore suggest that the organization of human color vision according to four-color classes (reds, greens, blues, and yellows) has arisen as a solution to this logical requirement in topology.

The effects of color on brightness

Observation of human subjects shows that the spectral returns of equiluminant colored surrounds govern the apparent brightness of achromatic test targets. The influence of color on brightness provides further evidence that perceptions of luminance are generated according to the empirical frequency of the possible sources of visual stimuli, and suggests a novel way of understanding color contrast and constancy.

An empirical explanation of the cornsweet effect

A long-standing puzzle in vision is the assignment of illusory brightness values to visual territories based on the characteristics of their edges (the Craik-O'Brien-Cornsweet effect). Here we show that the perception of the equiluminant territories flanking the Cornsweet edge varies according to whether these regions are more likely to be similarly illuminated surfaces having the same material properties or unequally illuminated surfaces with different properties. Thus, if the likelihood is increased that these territories are surfaces with similar reflectance properties under the same illuminant, the Craik-O'Brien-Cornsweet effect is diminished; conversely, if the likelihood is increased that the adjoining territories are differently reflective surfaces receiving different amounts of illumination, the effect is enhanced. These findings indicate that the Craik-O'Brien-Cornsweet effect is determined by the relative probabilities of the possible sources of the luminance profiles in the stimulus.

Interindividual variation in human visual performance

The responses of 20 young adult emmetropes with normal color vision were measured on a battery of visual performance tasks. Using previously documented tests of known reliability, we evaluated orientation discrimination, contrast sensitivity, wavelength sensitivity, vernier acuity, direction-of-motion detection, velocity discrimination, and complex form identification. Performance varied markedly between individuals, both on a given test and when the scores from all tests were combined to give an overall indication of visual performance. Moreover, individual performances on tests of contrast sensitivity, orientation discrimination, wavelength discrimination, and vernier acuity covaried, such that proficiency on one test predicted proficiency on the others. These results indicate a wide range of visual abilities among normal subjects and provide the basis for an overall index of visual proficiency that can be used to determine whether the surprisingly large and coordinated size differences of the components of the human visual system (Andrews, Halpern, & Purves, 1997) are reflected in corresponding variations in visual performance.

An empirical basis for Mach bands

Mach bands, the illusory brightness maxima and minima perceived at the initiation and termination of luminance gradients, respectively, are generally considered a direct perceptual manifestation of lateral inhibitory interactions among retinal or other lower order visual neurons. Here we examine an alternative explanation, namely that Mach bands arise as a consequence of real-world luminance gradients. In this first of two companion papers, we analyze the natural sources of luminance gradients, demonstrating that real-world gradients arising from curved surfaces are ordinarily adorned by photometric highlights and lowlights in the position of the illusory bands. The prevalence of such gradients provides an empirical basis for the generation of this perceptual phenomenon.

Mach bands as empirically derived associations

If Mach bands arise as an empirical consequence of real-world luminance profiles, several predictions follow. First, the appearance of Mach bands should accord with the appearance of naturally occurring highlights and lowlights. Second, altering the slope of an ambiguous luminance gradient so that it corresponds more closely to gradients that are typically adorned with luminance maxima and minima in the position of Mach bands should enhance the illusion. Third, altering a luminance gradient so that it corresponds more closely to gradients that normally lack luminance maxima and minima in the position of Mach bands should diminish the salience of the illusion. Fourth, the perception of Mach bands elicited by the same luminance gradient should be changed by contextual cues that indicate whether the gradient is more or less likely to signify a curved or a flat surface. Because each of these predictions is met, we conclude that Mach bands arise because the association elicited by the stimulus (the percept) incorporates these features as a result of past experience.

An empirical explanation of brightness

In this second part of our study on the mechanism of perceived brightness, we explore the effects of manipulating three-dimensional geometry. The additional scenes portrayed here demonstrate that the same luminance profile can elicit different sensations of brightness as a function of how the objects in the scene are arranged in space. This further evidence confirms the implication of the scenes presented in the accompanying paper, namely that sensations of relative brightness-including standard demonstrations of simultaneous brightness contrast-cannot arise by computations of local contrast. The most plausible explanation of the full range of perceptual phenomena we have described is an empirical strategy that links the luminance profile in a visual stimulus with an association (the percept) that represents the profile's most probable real-world source.

The influence of depicted illumination on brightness

The striking illusions produced by simultaneous brightness contrast generally are attributed to the center-surround receptive field organization of lower order neurons in the primary visual pathway. Here we show that the apparent brightness of test objects can be either increased or decreased in a predictable manner depending on how light and shadow are portrayed in the scene. This evidence suggests that perceptions of brightness are generated empirically by experience with luminance relationships, an idea whose implications we pursue in the accompanying paper.

The distribution of oriented contours in the real world

In both humans and experimental animals, the ability to perceive contours that are vertically or horizontally oriented is superior to the perception of oblique angles. There is, however, no consensus about the developmental origins or functional basis of this phenomenon. Here, we report the analysis of a large library of digitized scenes using image processing with orientation-sensitive filters. Our results show a prevalence of vertical and horizontal orientations in indoor, outdoor, and even entirely natural settings. Because visual experience is known to influence the development of visual cortical circuitry, we suggest that this real world anisotropy is related to the enhanced ability of humans and other animals to process contours in the cardinal axes, perhaps by stimulating the development of a greater amount of visual circuitry devoted to processing vertical and horizontal contours.

Unequal representation of cardinal and oblique contours in ferret visual cortex

We have measured the amount of cortical space activated by differently oriented gratings in 25 adult ferrets by optical imaging of intrinsic signal. On average, 7% more area of the exposed visual cortex was preferentially activated by vertical and horizontal contours than by contours at oblique angles. This anisotropy may reflect the real-world prevalence of contours in the cardinal axes and could explain the greater sensitivity of many animals to vertical and horizontal stimuli.

Similarities in normal and binocularly rivalrous viewing

We report here a series of observations-most of which the reader can experience directly-showing that distinct components of patterned visual stimuli (orthogonal lines of a different hue) vary in perception as sets. Although less frequent and often less complete, these perceptual fluctuations in normal viewing are otherwise similar to the binocular rivalry experienced when incompatible scenes are presented dichoptically.

The perception of transparent three-dimensional objects

When the proximal and distal elements of wire-frame cubes are conflated, observers perceive illusory structures that no longer behave veridically. These phenomena suggest that what we normally see depends on visual associations generated by experience. The necessity of such learning may explain why the mammalian visual system is subject to a prolonged period of plasticity in early life, when novel circuits are made in enormous numbers.

Correlated size variations in human visual cortex, lateral geniculate nucleus, and optic tract

We have examined several components of the human visual system to determine how the dimensions of the optic tract, lateral geniculate nucleus (LGN), and primary visual cortex (V1) vary within the same brain. Measurements were made of the cross-sectional area of the optic tract, the volumes of the magnocellular and parvocellular layers of the LGN, and the surface area and volume of V1 in one or both cerebral hemispheres of 15 neurologically normal human brains obtained at autopsy. Consistent with previous observations, there was a two- to threefold variation in the size of each of these visual components among the individuals studied. Importantly, this variation was coordinated within the visual system of any one individual. That is, a relatively large V1 was associated with a commensurately large LGN and optic tract, whereas a relatively small V1 was associated with a commensurately smaller LGN and optic tract. This relationship among the components of the human visual system indicates that the development of its different parts is interdependent. Such coordinated variation should generate substantial differences in visual ability among humans.