Varieties and regularities in the abundance patterns of the rareearth elements

Vision in the fovea, the center of the visual field, is much more accurate and detailed than vision in the periphery. This is not in line with the rich phenomenology of peripheral vision. Here, we investigated a visual illusion that shows that detailed peripheral visual experience is partially based on a reconstruction of reality. Participants fixated on the center of a visual display in which central stimuli differed from peripheral stimuli. Over time, participants perceived that the peripheral stimuli changed to match the central stimuli, so that the display seemed uniform. We showed that a wide range of visual features, including shape, orientation, motion, luminance, pattern, and identity, are susceptible to this uniformity illusion. We argue that the uniformity illusion is the result of a reconstruction of sparse visual information (from the periphery) based on more readily available detailed visual information (from the fovea), which gives rise to a rich, but illusory, experience of peripheral vision

Prospectively reinstated memory drives conscious access of matching visual input

Item does not contain fulltextMaintaining information in visual working memory (VWM) biases attentional selection of concurrent visual input, by favoring VWM-matching over VWM-mismatching visual input. Recently, it was shown that this bias disappears when the same item is memorized on consecutive occasions (as memoranda presumably transit from VWM to long-term memory), but reemerges when observers anticipate to memorize a novel item on a subsequent trial. Here, we aimed to conceptually replicate and extend this intriguing finding, by investigating whether prospectively reinstated memory drives conscious access of memory-matching visual input. We measured the time it took for participants to detect interocularly suppressed target stimuli, which were either from the same color category as a concurrently memorized color or not. Our results showed that the advantage of memory-matching targets in overcoming suppression progresses non-monotonically across consecutive memorizations of the same color ('repetitions'): the advantage for memory-matching visual input initially declined to asymptote, before being fully revived on the last repetition. This revival was not observed in a control experiment in which targets were not interocularly suppressed. The results suggest that, as observers anticipate to memorize a novel item imminently, VWM usage is prospectively reinstated, causing memory-matching visual input to gain accelerated access to consciousness again.12 p

Binocular rivalry in context

In the thesis ‘binocular rivalry in context’, we discuss how binocular rivalry is affected by its visual surround. This approach enables us to answer the following question: how does a visual surround affect (local) visual perception? Several experiments described in this dissertation show that binocular rivalry can be affected by visual context. Visual context can both modulate dominance durations of rival targets and can affect the amount by which rival targets are suppressed. Visual context affected binocular rivalry in a manner closely in agreement with observations from neurophysiology. At high contrast, dominance of a rival target sharing its defining feature with the surround was lowered. At low contrast, a surround boosted the dominance of a target with the same defining feature. This finding corresponds with adaptive center-surround interactions observed at the neuronal level. In addition, these adaptive center-surround interactions are likely to be a general property of visual processing since they were observed for stimuli defined by motion, orientation and color. We have also shown that the influence of visual context on visual perception is dependent on visual attention. Dominance durations of rival targets increased when performing a task on stimuli presented in the surround. Again, this result is in accordance with results from neurophysiology: the way the neural response to a visual stimulus is affected by attention is similar to the effect of changing the contrast of the stimulus. The results provide possible insights into the following question: how does the visual system efficiently code visual information under a variety of viewing conditions? The surround interactions described in this dissertation provide a possible solution to this problem. When contrast is low, the neural signal is amplified, when contrast is high, this signal is lowered. This adaptive interaction between context and local visual information might enable us to perceive the visual world efficiently under a variety of visibility conditions. A similar argument can be made for the role of visual attention. While inspecting the visual world, we often wish to attend to multiple objects. Our experiments suggest that the signal for a stimulus increases if more attentional resources are available. The results of this dissertation also provide insights into the phenomenon of binocular rivalry. Binocular rivalry is evidently not independent of stimuli presented in the proximity of the rival targets. In addition, the results provide new insights into the relation between binocular rivalry and visual attention. Dominance durations during binocular rivalry are dependent on the amount of visual attention available for tracking binocular rivalry; diverting attention lengthens dominance durations. The results also provide an account for the limited control over binocular rivalry reported in the past. While trying to hold a target dominant by attention, the ability to do so is limited by a lower-level effect of attention, which speeds rivalry alternations. In conclusion, this dissertation provides evidence that visual context can modulate visual perception in a manner similar to how visual context affects visual processing at the neural level. Although it is generally not possible to study the influence of visual context at the level of individual neurons in humans, the results reported in this dissertation point towards a similar neural organization underlying contextual modulation of visual processing in humans as that observed in non-human species

An introduction to the philosophy of science

This is an essay about the philosophy of science, within the context of teaching it to year one of an academic psychology program.</p

Attention Gates the Selective Encoding of Duration

The abundance of temporal information in our environment calls for the e ective selection and utilization of temporal information that is relevant for our behavior. Here we investigated whether visual attention gates the selective encoding of relevant duration information when multiple sources of duration information are present. We probed the encoding of duration by using a duration-adaptation paradigm. Participants adapted to two concurrently presented streams of stimuli with di erent durations, while detecting oddballs in one of the streams. We measured the resulting duration after- e ect (DAE) and found that the DAE re ects stronger relative adaptation to attended durations, compared to unattended durations. Additionally, we demonstrate that unattended durations do not contribute to the measured DAE. These results suggest that attention plays a crucial role in the selective encoding of duration: attended durations are encoded, while encoding of unattended durations is either weak or absent

Attention Gates the Selective Encoding of Duration

The abundance of temporal information in our environment calls for the e ective selection and utilization of temporal information that is relevant for our behavior. Here we investigated whether visual attention gates the selective encoding of relevant duration information when multiple sources of duration information are present. We probed the encoding of duration by using a duration-adaptation paradigm. Participants adapted to two concurrently presented streams of stimuli with di erent durations, while detecting oddballs in one of the streams. We measured the resulting duration after- e ect (DAE) and found that the DAE re ects stronger relative adaptation to attended durations, compared to unattended durations. Additionally, we demonstrate that unattended durations do not contribute to the measured DAE. These results suggest that attention plays a crucial role in the selective encoding of duration: attended durations are encoded, while encoding of unattended durations is either weak or absent

Visual working memory storage recruits sensory processing areas

Item does not contain fulltextHuman visual processing is subject to a dynamic influx of visual information. Visual working memory (VWM) allows for maintaining relevant visual information available for subsequent behavior. According to the dominating view, VWM recruits sensory processing areas to maintain this visual information online (i.e., the 'sensory recruitment' hypothesis). In her recent Trends in Cognitive Sciences article, however, Xu [1] proposes that VWM storage does not rely on (occipital) sensory processing areas, but rather on specialized frontal and parietal areas that are not involved in sensory processing per se [1].2 p