Saliency Benchmarking Made Easy: Separating Models, Maps and Metrics

Dozens of new models on fixation prediction are published every year and compared on open benchmarks such as MIT300 and LSUN. However, progress in the field can be difficult to judge because models are compared using a variety of inconsistent metrics. Here we show that no single saliency map can perform well under all metrics. Instead, we propose a principled approach to solve the benchmarking problem by separating the notions of saliency models, maps and metrics. Inspired by Bayesian decision theory, we define a saliency model to be a probabilistic model of fixation density prediction and a saliency map to be a metric-specific prediction derived from the model density which maximizes the expected performance on that metric given the model density. We derive these optimal saliency maps for the most commonly used saliency metrics (AUC, sAUC, NSS, CC, SIM, KL-Div) and show that they can be computed analytically or approximated with high precision. We show that this leads to consistent rankings in all metrics and avoids the penalties of using one saliency map for all metrics. Our method allows researchers to have their model compete on many different metrics with state-of-the-art in those metrics: "good" models will perform well in all metrics.Comment: published at ECCV 201

How are complex cell properties adapted to the statistics of natural stimuli?

Kording KP, Kayser C, Einhauser W, Konig P. How are complex cell properties adapted to the statistics of natural stimuli? J Neurophysiol. 2004;91(1):206-12

Visual Saliency as an aid to updating digital maps

Visual attention is considered in the context of a professional computer-based task, using aerial photography for updating topographic mapping data (photogrammetry). There is potential for using visual attention models to help develop various semi-automated ‘attention-aware’ support systems for this task, and these are discussed. An experimental study is described which examined the potential influence of expertise, image type and exposure duration on the role of visual saliency or salience (as calculated by Itti, L., & Koch, C. (2000). A saliency-based search mechanism for overt and covert shifts of visual attention. Vision Research, 40, 1389–1506 saliency maps) in the distribution of visual attention with such imagery. Using a non-intrusive, low-resolution and low-cost method to determine the approximate distribution of visual attention, effects of expertise and landscape type were found. Unexpectedly, saliency appeared to be more relevant to visual attention among expert users than novices, and potential reasons for this are explored. Implications and further research plans are discussed

SARS-CoV-2 Spike Protein Stabilized in the Closed State Induces Potent Neutralizing Responses

The majority of SARS-CoV-2 vaccines in use or advanced developmentare based on the viral spike protein (S) as their immunogen. S is present on virionsas prefusion trimers in which the receptor binding domain (RBD) is stochasticallyopen or closed. Neutralizing antibodies have been described against both open andclosed conformations. The long-term success of vaccination strategies depends uponinducing antibodies that provide long-lasting broad immunity against evolvingSARS-CoV-2 strains. Here, we have assessed the results of immunization in a mousemodel using an S protein trimer stabilized in the closed state to prevent full expo-sure of the receptor binding site and therefore interaction with the receptor. Wecompared this with other modified S protein constructs, including representativesused in current vaccines. We found that all trimeric S proteins induced a T cellresponse and long-lived, strongly neutralizing antibody responses against 2019SARS-CoV-2 and variants of concern P.1 and B.1.351. Notably, the protein bindingproperties of sera induced by the closed spike differed from those induced bystandard S protein constructs. Closed S proteins induced more potent neutralizingresponses than expected based on the degree to which they inhibit interactionsbetween the RBD and ACE2. These observations suggest that closed spikes recruitdifferent, but equally potent, immune responses than open spikes and that this islikely to include neutralizing antibodies against conformational epitopes present inthe closed conformation. We suggest that closed spikes, together with their improved sta-bility and storage properties, may be a valuable component of refined, next-generationvaccines