Postdoctoral position in Human Psychophysics with TMS and/or EEG (m/f/d) (TV-L E13, 100%) Faculty of Science, University of Tübingen and Max Planck Institute for Biological Cybernetics, working group of Prof. Li Zhaoping. We are looking for highly skilled and motivated individuals to work on projects aimed towards understanding visual attentional and perceptual processes using TMS and/or EEG methodologies. The framework and motivation of the projects can be found at http://www.lizhaoping.org/zhaoping/AGZL_HumanVisual.html . The projects can involve, for example, visual search tasks, stereo vision tasks, visual illusions, and will be discussed during the application process. TMS and/or EEG methodologies can be used in combination with fMRI/MRI, eye tracking, and other related methods as necessary. The postdoc will be working closely with the principal investigator and other members of Zhaoping's team when needed. We are currently hiring for a Postdoctoral position in Human Psychophysics with TMS and/or EEG (m/f/d) (TV-L E13, 100%) to join us at the next possible opportunity. Responsibilities: - Conduct and participate in research projects such as lab and equipment set up, data collection, data analysis, writing reports and papers, and presenting at scientific conferences. - Participate in routine laboratory operations, such as planning and preparations for experiments, lab maintenance and lab procedures. - Coordinate with the PI and other team members for strategies and project planning. - Coordinate with the PI and other team members for project planning, and in supervision of student projects or teaching assistance for university courses in our field. Your application: The position is available immediately and will be open until filled. Preference will be given to applications received by November 30, 2021. We look forward to receiving your application that includes a cover letter, your curriculum vitae, relevant certificates, and three names and contacts for reference letters) electronically only through this job portal (https://jobs.tue.mpg.de/jobs/148). Informal inquiries can be addressed to jobs.li@tuebingen.mpg.de. Please note that incomplete applications will not be considered.

Postdoctoral position in Human Psychophysics with High field and/or 3T fMRI (TVöD-Bund E13, 100%) Max Planck Institute for Biological Cybernetics, department of Prof. Li Zhaoping (Dept of Sensory and Sensormotor systems), in collaboration with Prof. Klaus Scheffler (Dept of High-field magnetic resonance imaging), is looking for a highly skilled and motivated individual to work on projects to probe the hierarchical feedforward and feedback brain networks behind visual attentional and perceptual processes using human psychophysics techniques and High-field or 3T fMRI methodologies (e.g., laminar fMRI). The framework and motivation of the projects can be found at http://www.lizhaoping.org/zhaoping/AGZL_HumanVisual.html . The visual processes can involve, for example, visual search tasks, stereo vision tasks, visual illusions, and will be discussed during the application process. When needed, TMS and/or EEG, eye tracking, and other methodologies can be used in combination with fMRI/MRI. The postdoc will be working closely with the principal investigators and other members of their teams. We are currently hiring for a Postdoctoral position in Human Psychophysics with High field and/or 3T fMRI (m/f/d) (TV-L E13, 100%) to join us at the next opportunity. Responsibilities: - Conduct and participate in research projects such as lab and equipment set up, data collection, data analysis, writing reports and papers, and presenting at scientific conferences. - Participate in routine laboratory operations, such as planning and preparations for experiments, lab maintenance and lab procedures. - Coordinate with the PIs and other team members for strategies and project planning.- Participate in mentoring and supervision of student projects. Your application: The position is available immediately and will be open until filled. Preference will be given to applications received by November 30, 2021. We look forward to receiving your application that includes a cover letter, your curriculum vitae, relevant certificates, and three names and contacts for reference letters) electronically only through this job portal (https://jobs.tue.mpg.de/jobs/149). Informal inquiries can be addressed to jobs.li@tuebingen.mpg.de. Please note that incomplete applications will not be considered.

The talk will give a tour of Guided Search 6.0 (GS6), the latest evolution of the Guided Search model of visual search. Part 1 describes The Mechanics of Search. Because we cannot recognize more than a few items at a time, selective attention is used to prioritize items for processing. Selective attention to an item allows its features to be bound together into a representation that can be matched to a target template in memory or rejected as a distractor. The binding and recognition of an attended object is modeled as a diffusion process taking > 150 msec/item. Since selection occurs more frequently than that, it follows that multiple items are undergoing recognition at the same time, though asynchronously, making GS6 a hybrid serial and parallel model. If a target is not found, search terminates when an accumulating quitting signal reaches a threshold. Part 2 elaborates on the five sources of Guidance that are combined into a spatial “priority map” to guide the deployment of attention (hence “guided search”). These are (1) top-down and (2) bottom-up feature guidance, (3) prior history (e.g. priming), (4) reward, and (5) scene syntax and semantics. Finally, in Part 3, we will consider the internal representation of what we are searching for; what is often called “the search template”. That search template is really two templates: a guiding template (probably in working memory) and a target template (in long term memory). Put these pieces together and you have GS6.

A striking range of individual differences has been reported in a variety of visual search tasks, which naturally leads to the idea that some people are better at finding things than others. However, this conclusion appears to be premature. We carried out a replication of three recent visual search experiments and found that each task showed a wide range of individual differences as predicted, and observed good test-retest reliability in all three. However, performance on any one task was not correlated with the performance in the others: participants who naturally adopt efficient search strategies in one paradigm may perform at chance in another! Furthermore, we also show that behaviour in different versions of the same paradigm can be radically different: When simple line segments are used for search items, a large range of search strategies are found. If we instead use more complex search items, all our participants effortlessly adopt an optimal strategy. These results suggest search strategies are stable over time, but context-specific. To understand visual search we, therefore, need to account not only for differences between individuals but also how individuals interact with the search task and context.

Visual attention refers to a set of processes allowing selection of relevant and filtering out of irrelevant information in the visual environment. A large amount of research on visual attention has involved visual search paradigms, where observers are asked to report whether a single target is present or absent. However, recent studies have revealed that these classic single-target visual search tasks only provide a snapshot of how attention is allocated in the visual environment, and that multitarget visual foraging tasks may capture the dynamics visual attention more accurately. In visual foraging, observers are asked to select multiple instances of multiple target types, as fast as they can. A critical question in foraging research concerns the factors driving the next target selection. Most likely, this would require two steps: (1) identifying a set of candidates for the next selection, and (2) selecting the best option among these candidates. After having briefly described the advantage of visual foraging over visual search, I will review recent visual foraging studies testing the influence of several manipulations (e.g., target crypticity, number of items, selection modality) on foraging behaviour. Overall, these studies revealed that the next target selection during visual foraging is determined by the competition between three factors: target value, target proximity, and priming of features. I will explain how the analysis of individual differences in foraging behaviour can provide important information, with the idea that individuals show by-default internal biases toward value, proximity and priming that determine their search strategy and behaviour.

Perception can be strongly serially-dependent (i.e. biased toward previously seen stimuli). Recently, serial dependencies in perception were proposed as a mechanism for perceptual stability, increasing the apparent continuity of the complex environments we experience in everyday life. For example, stable scene perception can be actively achieved by the visual system through global serial dependencies, a special kind of serial dependence between summary statistical representations. Serial dependence occurs also between emotional expressions, but it is highly selective for the same identity. Overall, these results further support the notion of serial dependence as a global, highly specialized, and purposeful mechanism. However, serial dependence could also be a deleterious phenomenon in unnatural or unpredictable situations, such as visual search in radiological scans, biasing current judgments toward previous ones even when accurate and unbiased perception is needed. For example, observers make consistent perceptual errors when classifying a tumor- like shape on the current trial, seeing it as more similar to the shape presented on the previous trial. In a separate localization test, observers make consistent errors when reporting the perceived position of an objects on the current trial, mislocalizing it toward the position in the preceding trial. Taken together, these results show two opposite sides of serial dependence; it can be a beneficial mechanism which promotes perceptual stability, but at the same time a deleterious mechanism which impairs our percept when fine recognition is needed.