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1. Microsaccade dynamics mediate perceptual alternation in Monet’s “Impression, Sunrise.”

   Alexander, Robert G.; Venkatakrishnan, Ashwin; Chanovas, Jordi; Macknik, Stephen L.; Martinez-Conde, Susana (November 2018, Society for Neuroscience Conference 2018)

   Troxler fading is described as the perceptual disappearance of stationary images, often in the visual periphery, during sustained fixation. Microsaccades have been shown to counteract and reverse the perceptual fading of contrived stimuli such as Gabor patches (Costela, McCamy, Macknik, Otero‐Millan, & Martinez-Conde, 2013; McCamy, Macknik, & Martinez‐Conde, 2014; McCamy et al., 2012). Here we demonstrate that microsaccadic dynamics similarly drive equivalent perceptual alternations in representational art. This approach can help deepen our understanding of masterpieces such as Claude Monet's “Impression, Sunrise” (“Impression, soleil levant”), in which a red sun rises over two small fishing boats in a port. Though the red sun appears perceptually brighter than the surrounding sky, Livingstone (2002) showed that the sun and the surrounding sky have the same approximate luminance. Equiluminance between an object and its background is known to facilitate Troxler fading. Accordingly, Safran & Landis (1998) noticed that staring at the sailor in Monet’s painting results in perceptual fading of the sun. We set out to assess whether the perceptual fading of the sun in “Impression, Sunrise” depends on microsaccade production. If so, it would indicate that the vanishing of the sun in Monet’s masterpiece represents an instantiation of Troxler fading in art. 

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2. Introducing desirable patches to initiate ecosystem transitions and accelerate ecosystem restoration

   https://doi.org/10.1002/eap.2910  

   Eppinga, Maarten B.; Michaels, Theo K.; Santos, Maria J.; Bever, James D. (December 2023, Ecological Applications)

   Abstract Meeting restoration targets may require active strategies to accelerate natural regeneration rates or overcome the resilience associated with degraded ecosystem states. Introducing desired ecosystem patches in degraded landscapes constitutes a promising active restoration strategy, with various mechanisms potentially causing these patches to become foci from which desired species can re‐establish throughout the landscape. This study considers three mechanisms previously identified as potential drivers of introduced patch dynamics: autocatalytic nucleation, directed dispersal, and resource concentration. These mechanisms reflect qualitatively different positive feedbacks. We developed an ecological model framework that compared how the occurrence of each mechanism was reflected in spatio‐temporal patch dynamics. We then analyzed the implications of these relationships for optimal restoration design. We found that patch expansion accelerated over time when driven by the autocatalytic nucleation mechanism, while patch expansion driven by the directed dispersal or resource concentration mechanisms decelerated over time. Additionally, when driven by autocatalytic nucleation, patch expansion was independent of patch position in the landscape. However, the proximity of other patches affected patch expansion either positively or negatively when driven by directed dispersal or resource concentration. For autocatalytic nucleation, introducing many small patches was a favorable strategy, provided that each individual patch exceeded a critical patch size. Introducing a single patch or a few large patches was the most effective restoration strategy to initiate the directed dispersal mechanism. Introducing many small patches was the most effective strategy for reaching restored ecosystem states driven by a resource concentration mechanism. Our model results suggest that introducing desirable patches can substantially accelerate ecosystem restoration, or even induce a critical transition from an otherwise stable degraded state toward a desired ecosystem state. However, the potential of this type of restoration strategy for a particular ecosystem may strongly depend on the mechanism driving patch dynamics. In turn, which mechanism drives patch dynamics may affect the optimal spatial design of an active restoration strategy. Each of the three mechanisms considered reflects distinct spatio‐temporal patch dynamics, providing novel opportunities for empirically identifying key mechanisms, and restoration designs that introduce desired patches in degraded landscapes according to these patch dynamics. 

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3. Why did Rubens add a parrot to Titian's The Fall of Man ? A pictorial manipulation of joint attention

   https://doi.org/10.1167/jov.24.4.1  

   Alexander, Robert G.; Venkatakrishnan, Ashwin; Chanovas, Jordi; Ferguson, Sophie; Macknik, Stephen L.; Martinez-Conde, Susana (April 2024, Journal of Vision)

   Almost 400 years ago, Rubens copied Titian's The Fall of Man, albeit with important changes. Rubens altered Titian's original composition in numerous ways, including by changing the gaze directions of the depicted characters and adding a striking red parrot to the painting. Here, we quantify the impact of Rubens's choices on the viewer's gaze behavior. We displayed digital copies of Rubens's and Titian's artworks—as well as a version of Rubens's painting with the parrot digitally removed—on a computer screen while recording the eye movements produced by observers during free visual exploration of each image. To assess the effects of Rubens's changes to Titian's composition, we directly compared multiple gaze parameters across the different images. We found that participants gazed at Eve's face more frequently in Rubens's painting than in Titian's. In addition, gaze positions were more tightly focused for the former than for the latter, consistent with different allocations of viewer interest. We also investigated how gaze fixation on Eve's face affected the perceptual visibility of the parrot in Rubens's composition and how the parrot's presence versus its absence impacted gaze dynamics. Taken together, our results demonstrate that Rubens's critical deviations from Titian's painting have powerful effects on viewers’ oculomotor behavior. 

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4. Species‐specific variation in germination rates contributes to spatial coexistence more than adult plant water use in four closely‐related annual flowering plants

   https://doi.org/10.1111/1365-2745.13408  

   James, Aubrie R.M.; Burnette, Timothy E.; Mack, Jasmine; James, David E.; Eckhart, Vincent M.; Geber, Monica A. (April 2020, Journal of Ecology)

   1. Spatial partitioning is a classic hypothesis to explain plant species coexistence, but evidence linking local environmental variation to spatial sorting, demography and species' traits is sparse. If co-occurring species' performance is optimized differently along environmental gradients because of trait variation, then spatial variation might facilitate coexistence. 2. We used a system of four naturally co-occurring species of Clarkia (Onagraceae) to ask whether distribution patchiness corresponds to variation in two environmental variables that contribute to hydrological variation. We then reciprocally sowed Clarkia into each patch type and measured demographic rates in the absence of congeneric competition. Species sorted in patches along one or both gradients, and in three of the four species, germination rate in the ‘home’ patch was higher than all other patches. 3. Spatially variable germination resulted in the same three species exhibiting the highest population growth rates in their home patches. 4. Species' trait values related to plant water use, as well as indicators of water stress in home patches, differed among species and corresponded to home patch attributes. However, post-germination survival did not vary among species or between patch types, and fecundity did not vary spatially. 5. Synthesis. Our research demonstrates the likelihood that within-community spatial heterogeneity affects plant species coexistence, and presents novel evidence that differential performance in space is explained by what happens in the germination stage. Despite the seemingly obvious link between adult plant water-use and variation in the environment, our results distinguish the germination stage as important for spatially variable population performance. 

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5. Poster Session I: Criterion effects in maximum likelihood difference scaling: Similar is not always the opposite of different

   https://doi.org/10.1167/jov.23.15.46  

   Shi, Yangyi; Eskew, Rhea (December 2023, Journal of Vision)

   Maximum Likelihood Difference Scaling (MLDS) is an efficient method of estimating perceptual representations of suprathreshold physical quantities (Maloney & Yang, 2003), such as luminance contrast. In MLDS, observers can be instructed to judge which of two stimulus pairs are more similar to one another, or which of the two pairs are more different from one another. If the same physical attributes are used for both the similar and dissimilar tasks, the two criteria should produce the same perceptual scales. We estimated perceptual scales for suprathreshold achromatic square patches. Increments and decrements on the mid-gray background were estimated separately. Observers judged which pair of stimuli were more similar in half of the sessions, and more different in the other half sessions. For most observers, the two tasks produced the same perceptual scales: a decelerating curve for increment contrasts and a cubic curve for decremental contrasts (cf. Whittle, 1992). These scales predicted forced-choice contrast discrimination thresholds for both increments and decrements. However, for a subset of observers, the ‘more different’ judgments produced scales that accelerated with contrast for both increments and decrements; these scale shapes do not predict their discrimination thresholds. Our results suggest that, even with these simple stimuli, observers in an MLDS experiment may attend to different aspects of the stimulus depending on the assigned task. 

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