News and Events

Perception and the strongest sensory memory trace of multi-stable displays both form shortly after the stimulus onset

Publication Type:

Journal Article

Source:

Attention, Perception, & Psychophysics, Springer US, p.1 - 11 (2015)

URL:

http://dx.doi.org/10.3758/s13414-015-1004-4

Keywords:

Implicit visual memory, Kinetic-depth effect, multi-stable perception, Perceptual inference, Perceptual memory, sensory memory, structure-from-motion

Abstract:

We investigated the relation between perception and sensory memory of multi-stable structure-from-motion displays. The latter is an implicit visual memory that reflects a recent history of perceptual dominance and influences only the initial perception of multi-stable displays. First, we established the earliest time point when the direction of an illusory rotation can be reversed after the display onset (29–114 ms). Because our display manipulation did not bias perception towards a specific direction of illusory rotation but only signaled the change in motion, this means that the perceptual dominance was established no later than 29–114 ms after the stimulus onset. Second, we used orientation-selectivity of sensory memory to establish which display orientation produced the strongest memory trace and when this orientation was presented during the preceding prime interval (80–140 ms). Surprisingly, both estimates point towards the time interval immediately after the display onset, indicating that both perception and sensory memory form at approximately the same time. This suggests a tighter integration between perception and sensory memory than previously thought, warrants a reconsideration of its role in visual perception, and indicates that sensory memory could be a unique behavioral correlate of the earlier perceptual inference that can be studied post hoc.

Transformation priming helps to disambiguate sudden changes of sensory inputs

Publication Type:

Journal Article

Source:

Vision Research, Volume 116, p.36–44 (2015)

URL:

http://www.sciencedirect.com/science/article/pii/S0042698915003065 http://linkinghub.elsevier.com/retrieve/pii/S0042698915003065

Keywords:

Attention, Perceptual inference, Priming, Prior knowledge, Shape-from-shading, Streaming-bouncing, structure-from-motion, Transformations, Visual memory, Visual Perception

Abstract:

Retinal input is riddled with abrupt transients due to self-motion, changes in illumination, object-motion, etc. Our visual system must correctly interpret each of these changes to keep visual perception consistent and sensitive. This poses an enormous challenge, as many transients are highly ambiguous in that they are consistent with many alternative physical transformations. Here we investigated inter-trial effects in three situations with sudden and ambiguous transients, each presenting two alternative appearances (rotation-reversing structure-from-motion, polarity-reversing shape-from-shading, and streaming-bouncing object collisions). In every situation, we observed priming of transformations as the outcome perceived in earlier trials tended to repeat in subsequent trials and this repetition was contingent on perceptual experience. The observed priming was specific to transformations and did not originate in priming of perceptual states preceding a transient. Moreover, transformation priming was independent of attention and specific to low level stimulus attributes. In summary, we show how "transformation priors"; and experience-driven updating of such priors helps to disambiguate sudden changes of sensory inputs. We discuss how dynamic transformation priors can be instantiated as "transition energies" in an "energy landscape" model of the visual perception.

Stochastic Accumulation by Cortical Columns May Explain the Scalar Property of Multistable Perception

Publication Type:

Journal Article

Source:

Physical Review Letters, Volume 113, Issue 9, p.098103 (2014)

URL:

http://link.aps.org/doi/10.1103/PhysRevLett.113.098103

Abstract:

The timing of certain mental events is thought to reflect random walks performed by underlying neural dynamics. One class of such events—stochastic reversals of multistable perceptions—exhibits a unique scalar property: even though timing densities vary widely, higher moments stay in particular proportions to the mean. We show that stochastic accumulation of activity in a finite number of idealized cortical columns—realizing a generalized Ehrenfest urn model—may explain these observations. Modeling stochastic reversals as the first-passage time of a threshold number of active columns, we obtain higher moments of the first-passage time density. We derive analytical expressions for noninteracting columns and generalize the results to interacting columns in simulations. The scalar property of multistable perception is reproduced by a dynamic regime with a fixed, low threshold, in which the activation of a few additional columns suffices for a reversal.

The Slow Science Manifesto

We are scientists. We don’t blog. We don’t twitter. We take our time.

Don’t get us wrong—we do say yes to the accelerated science of the early 21st century. We say yes to the constant flow of peer-review journal publications and their impact; we say yes to science blogs and media & PR necessities; we say yes to increasing specialization and diversification in all disciplines. We also say yes to research feeding back into health care and future prosperity. All of us are in this game, too.

However, we maintain that this cannot be all. Science needs time to think. Science needs time to read, and time to fail. Science does not always know what it might be at right now. Science develops unsteadi­ly, with jerky moves and un­predict­able leaps forward—at the same time, however, it creeps about on a very slow time scale, for which there must be room and to uk slots which justice must be done.

Slow science was pretty much the only science conceivable for hundreds of years; today, we argue, it deserves revival and needs protection. Society should give scientists the time they need, but more importantly, scientists must take their time.

We do need time to think. We do need time to digest. We do need time to mis­understand each other, especially when fostering lost dialogue between humanities and natural sciences. We cannot continuously tell you what our science means; what it will be good for; because we simply don’t know yet. Science needs time.

—Bear with us, while we think.

http://slow-science.org/

 

Perceptual adaptation to structure-from-motion depends on the size of adaptor and probe objects, but not on the similarity of their shapes

Publication Type:

Journal Article

Source:

Attention, perception & psychophysics, Volume 76, Issue 2, p.473-88 (2014)

URL:

http://link.springer.com/article/10.3758%2Fs13414-013-0567-1

Abstract:

<p>Perceptual adaptation destabilizes the phenomenal appearance of multistable visual displays. Prolonged dominance of a perceptual state fatigues the associated neural population, lowering the likelihood of renewed perception of the same appearance (Nawrot &amp; Blake in Perception &amp; Psychophysics, 49, 230–44, 1991). Here, we used a selective adaptation paradigm to investigate perceptual adaptation for the illusory rotation of ambiguous structure-from-motion (SFM) displays. Specifically, we generated SFM objects with different three-dimensional shapes and presented them in random order, separating successive objects by brief blank periods, which included a mask. To assess the specificity of perceptual adaptation to the shape of SFM objects, we established the probability that a perceived direction of rotation persisted between successive objects of similar or dissimilar shape. We found that the strength of negative aftereffects depended on the volume, but not the shape, of adaptor and probe objects. More voluminous objects were both more effective as adaptor objects and more sensitive as probe objects. Surprisingly, we found these volume effects to be completely independent, since any relationship between two shapes (such as overlap between volumes, similarity of shape, or similarity of velocity profiles) failed to modulate the negative aftereffect. This pattern of results was the opposite of that observed for sensory memory of SFM objects, which reflects similarity between objects, but not volume of individual objects (Pastukhov et al. inAttention, Perception &amp; Psychophysics, 75, 1215–1229, 2013). The disparate specificities of perceptual adaptation and sensory memory for identical SFM objects suggest that the two aftereffects engage distinct neural representations, consistent with recent brain imaging results (Schwiedrzik et al. in Cerebral Cortex, 2012).</p>

Sensory memory of illusory depth in structure-from-motion

Publication Type:

Journal Article

Source:

Attention, perception & psychophysics, Volume 76, Issue 1, p.123-32 (2014)

Keywords:

multi-stability, sensory memory, structure-from-motion

Abstract:

<p>When multistable displays (stimuli consistent with two or more equally plausible perceptual interpretations) are presented intermittently, their perceptions are stabilized by sensory memory. Independent memory traces are generated not only for different types of multistable displays (Maier, Wilke, Logothetis, &amp; Leopold, Current Biology 13:1076–1085, 2003), but also for different ambiguous features of binocular rivalry (Pearson &amp; Clifford, Journal of Vision 4:196–202, 2004). In the present study, we examined whether a similar independence of sensory memories is observed in structure-from-motion (SFM), a multistable display with two ambiguous properties. In SFM, a 2-D planar motion creates a vivid impression of a rotating 3-D volume. Both the illusory rotation and illusory depth (i.e., how close parts of an object appear to the observer) of an SFM object are ambiguous. We dissociated the sensory memories of these two ambiguous properties by using an intermittent presentation in combination with a forced-ambiguous-switch paradigm (Pastukhov, Vonau, &amp; Braun, PLoS ONE 7:e37734, 2012). We demonstrated that the illusory depth of SFM generates a sensory memory trace that is independent from that of illusory rotation. Despite this independence, the specificities levels of the sensory memories were identical for illusory depth and illusory rotation. The history effect was weakened by a change in the volumetric property of a shape (whether it was a hollow band or a filled drum volume), but not by changes in color or size. We discuss how these new results constrain models of sensory memory and SFM processing.</p>

Alexander Pastukhov receives "Best Article Award 2013"

Alexander Pastukhov receives "Best Article Award 2013"

The award is presented by the Psychonomic Society for the best contribution of the year in the prestigious scientific journal “Attention, Perception & Psychophysics” (August 2013).

Alexander Pastukhov

Alexander Pastukhov, Postdoc in the lab of Jochen Braun (Bernstein Group Magdeburg, Otto-von-Guericke-University Magdeburg), receives the award for his work on neural representation of three-dimensional visual objects. He was nominated for two different publications by two independent editors. At the moment, Alexander Pastukhov habilitates at the Center for Behavioral Brain Sciences, Magdeburg.

The award will be ceremonially conferred at the annual meeting of the Psychonomic Society in Toronto, Canada, in November 2013.

The nominated contributions are:

Pastukhov, A., & Braun, J. (2013). Structure-from-motion: dissociating perception, neural persistence, and sensory memory of illusory depth and illusory rotation. Attention, perception & psychophysics, 75 (2), p.322-40.

Pastukhov, A., Fullekrug, J., & Braun, J. (2013). Sensory memory of structure-from-motion is shape specific.Attention, perception & psychophysicsб 75(6), p. 1215-1229.

 

Jochen Braun participates in Marie Curie Network “INDIREA”

Jochen Braun participates in Marie Curie Network “INDIREA”

The Marie Curie Initial Training Network (ITN) “Individualized Diagnostics and Rehabilitation of Attention, INDIREA” focuses on improving the diagnosis and rehabilitation of neuropsychological disorders of attention (August 2013).

Jochen Braun an Marie Curie Network “INDIREA” beteiligt_140813

Jochen Braun
Image: Otto-von-Guericke-Universität Magdeburg

The ITN – coordinated by Glyn Humphreys, Oxford – will run over a period of 3.5 years and is supported by the EU with a total funding volume of over 3.7 M €. It will finance research projects and training opportunities of 13 PhD students.  Additionally, regular meetings and exchanges between partners will take place.

The network involves neuropsychologists, neuroscientists, and industry partners in Oxford, Munich, Copenhagen, Magdeburg, Barcelona, Dublin, and elsewhere. German contributing scientists are Jochen Braun (coordinator of the Bernstein Group Magdeburg) and Hermann Müller (LMU Munich).  The common goal is to deepen our understanding of the neurobiological basis of attention, by linking computational models, brain imaging information, and behavioral performance, and by applying the results to clinical procedures for diagnosis and rehabilitation.

 

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