Temporal integration of feature probability distributions

Testing temporal integration of feature probability distributions using role-reversal effects in visual search

Vision Research ◽

10.1016/j.visres.2021.07.012 ◽

2021 ◽

Vol 188 ◽

pp. 211-226

Author(s):

Ömer Dağlar Tanrıkulu ◽

Andrey Chetverikov ◽

Árni Kristjánsson

Keyword(s):

Visual Search ◽

Probability Distributions ◽

Temporal Integration ◽

Role Reversal ◽

Feature Probability

Download Full-text

Temporal integration of feature probability distributions in visual working memory

Journal of Vision ◽

10.1167/jov.21.9.1969 ◽

2021 ◽

Vol 21 (9) ◽

pp. 1969

Author(s):

Sabrina Hansmann-Roth ◽

Sóley Thorsteinsdóttir ◽

Joy Geng ◽

Árni Kristjánsson

Keyword(s):

Working Memory ◽

Visual Working Memory ◽

Probability Distributions ◽

Temporal Integration ◽

Feature Probability

Download Full-text

Temporal integration of feature probability distributions in working memory

10.31234/osf.io/2uy57 ◽

2020 ◽

Author(s):

Sabrina Hansmann-Roth ◽

Sóley Thorsteinsdóttir ◽

Joy Geng ◽

Arni Kristjansson

Keyword(s):

Visual Search ◽

Visual System ◽

Uniform Distribution ◽

Probability Distributions ◽

Temporal Integration ◽

Target Feature ◽

Target Distribution ◽

Distribution Shape ◽

Complex Target ◽

Feature Probability

Humans are surprisingly good at learning the characteristics of their visual environment. Recent studies have revealed that not only can the visual system learn repeated features of visual search distractors, but their actual probability distributions. Search times were determined by the frequency of distractor features over consecutive search trials. Distractor distributions involve many exemplars on each trial, but whether observers can learn distributions where only a single exemplar from the distribution is presented on each trial is unknown. Here, we investigated potential learning of probability distributions of single targets during visual search. Over blocks of trials observers searched for an oddly-colored target that was drawn from either a Gaussian or uniform distribution. Not only was search influenced by the repetition of a target feature but more interestingly also by the probability of that feature within trial blocks. The same search targets, coming from the extremes of the two distributions were found significantly slower during the blocks where the distractors were drawn from a Gaussian distribution than from a uniform distribution indicating that observers were sensitive to the target probability determined by the distribution shape. In Experiment 2 we replicated the effect using binned distributions and revealed the limitations of target distribution encoding by using a more complex target distribution. Our results demonstrate detailed internal representations of target feature distributions and that the visual system integrates probability distributions of target colors over surprisingly long trial sequences.

Download Full-text

Testing temporal integration of feature probability distributions using role-reversal effects in visual search

10.31234/osf.io/cynhw ◽

2020 ◽

Author(s):

Ömer Dağlar Tanrıkulu ◽

Andrey Chetverikov ◽

Arni Kristjansson

Keyword(s):

Visual Search ◽

Visual System ◽

Response Times ◽

Probability Distributions ◽

Temporal Integration ◽

Internal Representation ◽

Statistical Properties ◽

Role Reversal ◽

Sensory History ◽

Feature Probability

The visual system is sensitive to statistical properties of complex scenes and can encode feature probability distributions in detail. This encoding could reflect a passive process due to the visual system’s sensitivity to temporal perturbations in the input or a more active process of building probabilistic representations. To investigate this, we examined how observers temporally integrate two different orientation distributions from sequentially presented visual search trials. If the encoded probabilistic information is used in a Bayesian optimal way, observers should weigh more reliable information more strongly, such as feature distributions with low variance. We therefore manipulated the variance of the two feature distributions. Participants performed sequential odd-one-out visual search for an oddly oriented line among distractors. During successive learning trials, the distractor orientations were sampled from two different Gaussian distributions on alternating trials. Then, observers performed a ‘test trial’ where the orientations of the target and distractors were switched, allowing to assess observer’s internal representation of distractor distributions based on changes in response times. In three experiments we observed that observer’s search times on test trials depended mainly on the very last learning trial, indicating little temporal integration. Since temporal integration has been previously observed with this method, we conclude that when the input is unreliable, the visual system relies on the most recent stimulus instead of integrating it with previous ones. This indicates that the visual system prefers to utilize sensory history when the statistical properties of the environment are relatively stable

Download Full-text

Probabilistic Motion Estimation Based on Temporal Coherence

Neural Computation ◽

10.1162/089976600300015169 ◽

2000 ◽

Vol 12 (8) ◽

pp. 1839-1867 ◽

Cited By ~ 27

Author(s):

Pierre-Yves Burgi ◽

Alan L. Yuille ◽

Norberto M. Grzywacz

Keyword(s):

Computer Simulations ◽

Kalman Filtering ◽

Input Data ◽

Visual Motion ◽

Probability Distributions ◽

Temporal Integration ◽

Spatial Coherence ◽

Image Sequence ◽

Temporal Grouping ◽

Parallel Network

We develop a theory for the temporal integration of visual motion motivated by psychophysical experiments. The theory proposes that input data are temporally grouped and used to predict and estimate the motion flows in the image sequence. This temporal grouping can be considered a generalization of the data association techniques that engineers use to study motion sequences. Our temporal grouping theory is expressed in terms of the Bayesian generalization of standard Kalman filtering. To implement the theory, we derive a parallel network that shares some properties of cortical networks. Computer simulations of this network demonstrate that our theory qualitatively accounts for psychophysical experiments on motion occlusion and motion outliers. In deriving our theory, we assumed spatial factorizability of the probability distributions and made the approximation of updating the marginal distributions of velocity at each point. This allowed us to perform local computations and simplified our implementation. We argue that these approximations are suitable for the stimuli we are considering (for which spatial coherence effects are negligible).

Download Full-text

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

International Astronomical Union Colloquium ◽

10.1017/s0252921100014718 ◽

1997 ◽

Vol 161 ◽

pp. 197-201 ◽

Cited By ~ 1

Author(s):

Duncan Steel

Keyword(s):

Probability Distributions ◽

Regions Of Interest ◽

Significant Fraction ◽

Organic Chemicals ◽

Impact Speed ◽

The Mean ◽

The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Download Full-text