Biology subjects

Goddard, E.

Publications and source records attributed to Goddard, E..

9 recordsLinked to original sources

bioRxiv2026

Facial color properties affect perceived age.

Age is a fundamental social attribute that affects rights, responsibilities and even social status. Color information of the face can affect perceived age, but the nature of its contribution, independent of luminance information, remains underexplored. To better characterize the role of color in age perception, we conducted two experiments. In our first experiment, we tested whether natural age-related changes in facial color alone can drive changes in perceived age. In our second experiment, we manipulated red-green contrast across faces aged 18-91 and tested the effect of this manipulation of perceived youthfulness. Our findings demonstrate that natural age-related color changes do provide cues for age perception, dissociable from luminance information. We also found that the optimal red-green contrast level to make faces look the youngest was significantly higher than the originals, meaning that faces tended to appear younger when their redness was accentuated, even though average face redness increases with age. Our analysis revealed that younger faces required greater increases in redness level compared to their older counterparts to achieve the youngest appearance. These results suggest that the spatial distribution of redness contributes to apparent youthfulness, especially in younger faces.

neuroscience↗

bioRxiv2025

Attention biases the appearance of rapidly alternating stimuli

Attentional selection not only increases behavioural performance and neural information for attended stimuli but, in some instances, induces changes in stimulus appearance. While reported appearance changes have mostly concerned the effects of attending to a particular spatial location, here we report a shift in appearance that occurs when attention is directed to one component of a stimulus rapidly alternating at a single spatial location. Our stimuli included two frames of different colors, which alternated at 3.75Hz or 7.5Hz. Participants reported the perceived dominance of one frame's color in the reference stimulus, by comparison with a target stimulus. We found that when one stimulus frame was more salient than the other, with a greater likelihood of capturing exogenous attention, there was an illusory perception that the frame was physically present for a greater proportion of time. When the frames were matched in salience, a task encouraging participants to endogenously direct their attention to one frame produced a smaller shift in appearance. Our results add to the body of literature demonstrating that attention can change appearance, in this case altering the appearance of attended versus unattended stimuli that are presented at the same spatial location. Furthermore, our results demonstrate that at the 'temporal transparent' alternation rate of 7.5Hz, where rapidly alternating stimuli are perceived as two translucent surfaces, attentional selection of one surface can account for the apparent paradox that feature conjunctions are perceived at stimulus alternation rates higher than predicted by the temporal limits of feature binding for other stimuli.

neuroscience↗

bioRxiv2025

Perceiving surface colour requires attention

Colour constancy refers to our ability to distinguish changes in surface properties from changes in the properties of light illuminating the scene. The apparent ease with which we can tell that objects do not change in their surface properties, for example, when moving from sunlight to the shade, belies the complexity of solving this ill-constrained problem. Although there is a substantial body of work testing which image cues might be used to accomplish this, there is surprisingly little known of how the brain performs this computation. Here, we tested a fundamental aspect of the perceptual scission of surface reflectance from illuminant/filter properties: whether it requires attention. We measured visual search times for both surface reflectance (requiring separation of surface and illuminant properties) and local tristimulus value (which does not). We found a clear difference between the two: visual search for colour defined by tristimulus value was fast and near-parallel, while search for a particular surface reflectance was slow and consistent with the serial deployment of attention. That is, search times suggest that the perceptual separation of surface and illuminant or filter properties in colour constancy may require an attention-based process analogous to perceiving conjunctions of simple features in feature binding. These results offer important new insights into the sequence of processes the brain uses to accomplish colour constancy.

neuroscience↗

bioRxiv2024

Temporal evolution of color representations measured with MEG reveals a 'coarse to fine' dynamic

Color perception is based on the differential spectral responses of the L, M and S-cones, subsequent subcortical and cortical computations, and may include the influence of higher order factors such as language. Although the early subcortical stages of color vision are well characterised, the organization of cortical representations of color remain elusive, despite numerous models based on discrimination thresholds, appearance and categorization. An underexplored aspect of cortical color representations is their dynamic evolution. Here we compare the evolution of three different color representations over time using magnetoencephalography (MEG). We measured neural responses to 14 hues at each of 3 achromatic offsets (increment, isoluminant and decrement) while participants attended either to the exact color of the stimulus or its color category. We used a series of classification analyses, combined with multidimensional scaling (MDS) and Representational Similarity Analysis, to ask how cortical representations of color unfold over time from stimulus onset. We compared the performance of higher order models based on hue and color category with a model based simply on stimulus cone contrast and found that all models had significant correlations with the data. However, the unique variance accounted for by each model revealed a dynamic change in hue responses over time, that was consistent with a coarse to fine transition from a broad clustering into categorical groups to a finer within category representation. Notably, these dynamics were replicated across datasets from both tasks, suggesting they reflect a robust reorganization of cortical hue responses over time.

neuroscience↗

bioRxiv2024

Spatial and feature-selective attention interact to drive selective coding in frontoparietal cortex

Attention enables the selective processing of relevant information. Two types of selective attention, spatial and feature attention, have separable neural effects but in real life are often used together. Here, we asked how these types of attention interact to affect information coding in a frontoparietal multiple-demand (MD) network, essential for attentional control. Using functional magnetic resonance imaging (fMRI) with multivariate pattern analysis, we examined how covert attention to object features (colour or shape) and spatial locations (left or right) influences coding of task-related stimulus information. We found that spatial and feature attention interacted multiplicatively on information coding in MD and visual regions, such that there was above-chance decoding of the attended feature of the attended object and no detectable coding of visually equivalent but behaviourally irrelevant aspects of the visual display. The attended information had a multidimensional neural representation, with stimulus information (e.g., colour) and discrimination difficulty (distance from the categorical decision boundary) reflected in separate dimensions. Rather than boosting processing of whole objects or relevant features across space, our results suggest neural activity reflects precise tuning to relevant information, indicating a highly selective control process that codes behaviourally relevant information across multiple dimensions.

neuroscience↗

bioRxiv2021

Neural coding of visual objects rapidly reconfigures to reflect sub-trial shifts in attentional focus

Every day, we respond to the dynamic world around us by flexibly choosing actions to meet our goals. This constant problem solving, in familiar settings and in novel tasks, is a defining feature of human behaviour. Flexible neural populations are thought to support this process by adapting to prioritise task-relevant information, driving coding in specialised brain regions toward stimuli and actions that are important for our goal. Accordingly, human fMRI shows that activity patterns in frontoparietal cortex contain more information about visual features when they are task-relevant. However, if this preferential coding drives momentary focus, for example to solve each part of a task, it must reconfigure more quickly than we can observe with fMRI. Here we used MVPA with MEG to test for rapid reconfiguration of stimulus information when a new feature becomes relevant within a trial. Participants saw two displays on each trial. They attended to the shape of a first target then the colour of a second, or vice versa, and reported the attended features at a choice display. We found evidence of preferential coding for the relevant features in both trial phases, even as participants shifted attention mid-trial, commensurate with fast sub-trial reconfiguration. However, we only found this pattern of results when the task was difficult, and the stimulus displays contained multiple objects, and not in a simpler task with the same structure. The data suggest that adaptive coding in humans can operate on a fast, sub-trial timescale, suitable for supporting periods of momentary focus when complex tasks are broken down into simpler ones, but may not always do so.

neuroscience↗

bioRxiv2021

Pregnancy and weaning regulate human maternal liver size and function

BACKGROUNDDuring pregnancy, the rodent liver undergoes hepatocyte proliferation and increases in size, followed by weaning-induced involution via hepatocyte cell death and stromal remodeling, creating a pro-metastatic niche. These data suggest a mechanism for increased liver metastasis in postpartum breast cancer patients. OBJECTIVESInvestigate if the human liver changes in size and function during pregnancy and weaning. METHODSAbdominal imaging was obtained in healthy women at early and late pregnancy, and post-wean. During pregnancy time points, endogenous glucose production was measured and fasting blood taken to measure bile acids. RESULTSIndependent of weight gain, most womens livers increased in size with pregnancy, returning to baseline post-wean. Putative roles for bile acids in liver growth were observed in pregnant women and rodents. CONCLUSIONSThe human liver is regulated by reproductive state with growth during pregnancy and volume loss post-wean. These findings may have broad implications for sex-specific liver diseases and cancer.

physiology↗

bioRxiv2019

A humanness dimension to visual object coding in the brain

Neuroimaging studies investigating human object recognition have largely focused on a relatively small number of object categories, in particular, faces, bodies, scenes, and vehicles. More recent studies have taken a broader focus, investigating hypothesised dichotomies, for example animate versus inanimate, and continuous feature dimensions, such as biologically similarity. These studies typically have used stimuli that are clearly identified as animate or inanimate, neglecting objects that may not fit into this dichotomy. We generated a novel stimulus set including standard objects and objects that blur the animate-inanimate dichotomy, for example robots and toy animals. We used MEG time-series decoding to study the brains emerging representation of these objects. Our analysis examined contemporary models of object coding such as dichotomous animacy, as well as several new higher order models that take into account an objects capacity for agency (i.e. its ability to move voluntarily) and capacity to experience the world. We show that early brain responses are best accounted for by low-level visual similarity of the objects; and shortly thereafter, higher order models of agency/experience best explained the brains representation of the stimuli. Strikingly, a model of human-similarity provided the best account for the brains representation after an initial perceptual processing phase. Our findings provide evidence for a new dimension of object coding in the human brain - one that has a \"human-centric\" focus.

neuroscience↗

bioRxiv2019

Spatial and feature-selective attention have distinct effects on population-level tuning.

Attention is a fundamental brain process by which we selectively prioritize relevant information in our environment. Cognitively, we can employ different methods for selecting visual information for further processing, but the extent to which these are implemented by similar or different neural processes remains unclear. Spatial and feature-selective attention both change the stimulus related information signaled by single-cells and neural populations, but relatively few studies have directly compared the effects of these distinct types of attention. We scanned participants (n=20) using MEG, while they covertly attended to an object on the left or the right of fixation (spatial attention manipulation) and reported the objects shape or color (feature-selective attention manipulation). We used multivariate pattern classification to measure population stimulus-coding in occipital and frontal areas, for attended and non-attended stimulus features, at attended and non-attended locations. In occipital cortex, we show that both spatial and feature-selective attention enhanced object representations, and the effects of these two attention types interacted multiplicatively. We also found that spatial and feature-selective attention induced qualitatively different patterns of enhancement in occipital cortex for the encoding of stimulus color. Specifically, feature-based attention primarily enhanced small color differences, while spatial attention produced greater enhancement for larger differences. We demonstrate that principles of response-gain and tuning curve sharpening that have been applied to describe the effects of attention at the level of a single neuron can account for these differences. An information flow analysis suggested that these attentional effects may be driven by feedback from frontal areas.

neuroscience↗