The Effects of Coarseness of Quantisation, Exposure Duration, and Selective Spatial Attention on the Perception of Spatially Quantised (‘Blocked’) Visual Images

Perception ◽  
1997 ◽  
Vol 26 (9) ◽  
pp. 1181-1196 ◽  
Author(s):  
Talis Bachmann ◽  
Neeme Kahusk
Keyword(s):  
Spatial Attention ◽  
Time Course ◽  
Spatial Scales ◽  
Stimulus Onset ◽  
Visual Images ◽  
Attentional Processing ◽  
Abrupt Decrease ◽  
A Minor ◽  
Onset Asynchrony ◽  
Coarse To Fine

The two objectives of the present article are (a) to present a brief overview of the effects of systematic variation of the spatial-scale value of quantisation and stimulus duration on the identification of original images that have been degraded by Harmon–Julesz type of image pixelisation by ‘blocking’ and (b) to report the results of two experiments where the effects of selective spatial precuing by local and global peripheral precues on the identification of quantised target stimuli have been studied. Both the overview and the new results reported here demonstrate some counterintuitive effects: (1) abrupt decrease in identification efficiency with only a minor change in the coarseness of quantisation over a critical value of pixels per stimulus; (2) a cost for valid attentional precuing with coarse-quantised images. If physical precues (exposed with stimulus onset asynchrony of 120 ms) were employed in order to orient spatial attention to perceive original or fine-quantised stimuli, then attentional facilitation was found. However, if the precued stimuli were coarse quantised then the facilitative effect crossed over to a detrimental effect of attention. These effects are discussed in the context of the microgenetic approach that presupposes the existence of a perceptual–attentional processing routine that operates according to the coarse-to-fine time-course rule of selective attentional activation of stimulus representations at various spatial scales.

scholarly journals Multisensory Spatial Attention Deficits Are Predictive of Phonological Decoding Skills in Developmental Dyslexia

2010 ◽  
Vol 22 (5) ◽  
pp. 1011-1025 ◽  
Author(s):  
Andrea Facoetti ◽  
Anna Noemi Trussardi ◽  
Milena Ruffino ◽  
Maria Luisa Lorusso ◽  
Carmen Cattaneo ◽  
...  
Keyword(s):  
Spatial Attention ◽  
Developmental Dyslexia ◽  
Time Course ◽  
Reading Performance ◽  
Reading Level ◽  
Decoding Skills ◽  
Attentional Processing ◽  
Phonological Decoding ◽  
Decoding Accuracy ◽  
Deficit Theory

Although the dominant approach posits that developmental dyslexia arises from deficits in systems that are exclusively linguistic in nature (i.e., phonological deficit theory), dyslexics show a variety of lower level deficits in sensory and attentional processing. Although their link to the reading disorder remains contentious, recent empirical and computational studies suggest that spatial attention plays an important role in phonological decoding. The present behavioral study investigated exogenous spatial attention in dyslexic children and matched controls by measuring RTs to visual and auditory stimuli in cued-detection tasks. Dyslexics with poor nonword decoding accuracy showed a slower time course of visual and auditory (multisensory) spatial attention compared with both chronological age and reading level controls as well as compared with dyslexics with slow but accurate nonword decoding. Individual differences in the time course of multisensory spatial attention accounted for 31% of unique variance in the nonword reading performance of the entire dyslexic sample after controlling for age, IQ, and phonological skills. The present study suggests that multisensory “sluggish attention shifting”—related to a temporoparietal dysfunction—selectively impairs the sublexical mechanisms that are critical for reading development. These findings may offer a new approach for early identification and remediation of developmental dyslexia.

scholarly journals Rapid orienting of spatial attention toward and away from aggressive voices

2017 ◽  
Author(s):  
Nicolas Burra ◽  
Dirk Kerzel ◽  
David Munoz ◽  
Didier Grandjean ◽  
Leonardo Ceravolo
Keyword(s):  
Spatial Attention ◽  
Auditory Processing ◽  
Temporal Dynamics ◽  
Detection System ◽  
Stimulus Onset ◽  
Event Related Potential ◽  
Auditory Modality ◽  
Attentional Processing ◽  
Auditory Spatial Attention ◽  
Vocal Signals

Salient vocalizations, especially aggressive voices, are believed to attract attention due to an automatic threat detection system. However, studies assessing the temporal dynamics of auditory spatial attention to aggressive voices are missing. Using event-related potential markers of auditory spatial attention (N2ac and LPCpc), we show that attentional processing of threatening vocal signals is enhanced at two different stages of auditory processing. As early as 200 ms post stimulus onset, attentional orienting/engagement is enhanced for threatening as compared to happy vocal signals. Subsequently, as early as 400 ms post stimulus onset, the reorienting of auditory attention to the center of the screen (or disengagement from the target) is enhanced. This latter effect is consistent with the need to optimize perception by balancing the intake of stimulation from left and right auditory space. Our results extend the scope of theories from the visual to the auditory modality by showing that threatening stimuli also bias early spatial attention in the auditory modality. Although not the focus of the present work, we observed that the attentional enhancement was more pronounced in female than male participants.

The Time Course of Spatial Attention

2014 ◽  
Author(s):  
Martin Eimer
Keyword(s):  
Selective Attention ◽  
Spatial Attention ◽  
Time Course ◽  
Attentional Processing ◽  
Brain Potential ◽  
The Past ◽  
Technical Review

Event-related brain potential (ERP) measures have made important contributions to our understanding of the mechanisms of selective attention. This chapter provides a selective and non-technical review of some of these contributions. It will concentrate mainly on research that has studied spatially selective attentional processing in vision, although research on crossmodal links in spatial attention will also be discussed. The main purpose of this chapter is to illustrate how ERP methods have helped to provide answers to major theoretical questions that have shaped research on selective attention in the past 40 years.

scholarly journals Time Course of Forward Masking Tuning Curves in Cat Primary Auditory Cortex

1997 ◽  
Vol 77 (2) ◽  
pp. 923-943 ◽  
Author(s):  
Michael Brosch ◽  
Christoph E. Schreiner
Keyword(s):  
Receptive Field ◽  
Auditory Cortex ◽  
Stimulus Onset Asynchrony ◽  
Time Course ◽  
Tuning Curve ◽  
Primary Auditory Cortex ◽  
Stimulus Onset ◽  
Cortical Cells ◽  
Tuning Curves ◽  
Onset Asynchrony

Brosch, Michael and Christoph E. Schreiner. Time course of forward masking tuning curves in cat primary auditory cortex. J. Neurophysiol. 77: 923–943, 1997. Nonsimultaneous two-tone interactions were studied in the primary auditory cortex of anesthetized cats. Poststimulatory effects of pure tone bursts (masker) on the evoked activity of a fixed tone burst (probe) were investigated. The temporal interval from masker onset to probe onset (stimulus onset asynchrony), masker frequency, and intensity were parametrically varied. For all of the 53 single units and 58 multiple-unit clusters, the neural activity of the probe signal was either inhibited, facilitated, and/or delayed by a limited set of masker stimuli. The stimulus range from which forward inhibition of the probe was induced typically was centered at and had approximately the size of the neuron's excitatory receptive field. This “masking tuning curve” was usually V shaped, i.e., the frequency range of inhibiting masker stimuli increased with the masker intensity. Forward inhibition was induced at the shortest stimulus onset asynchrony between masker and probe. With longer stimulus onset asynchronies, the frequency range of inhibiting maskers gradually became smaller. Recovery from forward inhibition occurred first at the lower- and higher-frequency borders of the masking tuning curve and lasted the longest for frequencies close to the neuron's characteristic frequency. The maximal duration of forward inhibition was measured as the longest period over which reduction of probe responses was observed. It was in the range of 53–430 ms, with an average of 143 ± 71 (SD) ms. Amount, duration and type of forward inhibition were weakly but significantly correlated with “static” neural receptive field properties like characteristic frequency, bandwidth, and latency. For the majority of neurons, the minimal inhibitory masker intensity increased when the stimulus onset asynchrony became longer. In most cases the highest masker intensities induced the longest forward inhibition. A significant number of neurons, however, exhibited longest periods of inhibition after maskers of intermediate intensity. The results show that the ability of cortical cells to respond with an excitatory activity depends on the temporal stimulus context. Neurons can follow higher repetition rates of stimulus sequences when successive stimuli differ in their spectral content. The differential sensitivity to temporal sound sequences within the receptive field of cortical cells as well as across different cells could contribute to the neural processing of temporally structured stimuli like speech and animal vocalizations.

The Cost of Spatial-Attentional Precuing for the Perception of Spatially Quantised Visual Images

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 4-4
Author(s):  
T Bachmann ◽  
N Kahusk
Keyword(s):  
Stimulus Onset ◽  
Visual Images ◽  
Facilitative Effect ◽  
Target Image ◽  
Spatial Filters ◽  
Facial Identity ◽  
Target Stimulus Onset Asynchrony ◽  
The Cost ◽  
Onset Asynchrony ◽  
Facial Images

We have investigated the effects of selective attentional spatial precuing and levels of quantisation on the perception of spatially quantised visual images of faces. The coarseness (number of square-shaped isoluminant pixels per image) of quantisation of eight alternative facial images was systematically varied from 9 to 16 pixels per image (along the horizontal dimension). 16 grey levels of the image were used; both local and global precues that designated the position of the expected stimulus-image were employed. Precue-to-target stimulus onset asynchrony was equal to 120 ms, and target image duration was varied between 28 and 76 ms. Targets were exposed at one of four quasiperipheral positions, either after the precue or without the precue. It was found that precues had a facilitative effect on identification with fine levels of quantisation or with original images, but this changed to a cost for precuing with coarse levels (9 – 11 pixels per image). A dramatic drop in overall identification efficiency with moving from 12 pixels per image to 11 pixels per image condition was also revealed. The results are interpreted as supporting (1) the idea of gradual coarse-to-detailed presetting of spatial filters by the precue, and (2) the existence of some implicit relational metrics of the critical facial identity cues that can be ‘catastrophically’ disintegrated by a small but critical change in quantisation value.

Attention Effects on Form Discrimination at Different Eccentricities

1989 ◽  
Vol 41 (4) ◽  
pp. 719-746 ◽  
Author(s):  
MaryLou Cheal ◽  
Don Lyon
Keyword(s):  
Time Course ◽  
Target Location ◽  
Short Soas ◽  
Stimulus Onset ◽  
Attention Shifting ◽  
Form Discrimination ◽  
Discrimination Accuracy ◽  
Target Stimulus Onset Asynchrony ◽  
Time Course Of Attention ◽  
Onset Asynchrony

Considerable disagreement exists in the visual attention literature about how attention is allocated over the visual field. One frequently expressed metaphor is that attention moves like a spotlight, and in some variants it is assumed that attention takes longer to shift to targets further from fixation. In order to test this metaphor, five experiments were conducted in which target location was precued and form discrimination accuracy was assessed. By varying the interval between the precue and the target (stimulus onset asynchrony, SOA), a time course of attention effects was obtained for targets at 2°, 6°, and 10° eccentricity. In the first three experiments, precueing effects were found, but there were no differences in performance as a function of eccentricity for very short SOAs, with either a peripheral cue or a foveal arrow cue. For long SOAs, however, performance was better for targets that were closer to fixation. In Experiments 4 (peripheral cue) and 5 (foveal cue), the targets were scaled to make them equally discriminable at all eccentricities. Again precueing effects were found, but there were no differences in accuracy as a function of eccentricity for most SOAs. These results suggest that attention shifting is not analogous to a constant-velocity moving spotlight.

scholarly journals How Does Spatial Attention Influence the Probability and Fidelity of Colour Perception?

Vision ◽  
2019 ◽  
Vol 3 (2) ◽  
pp. 31
Author(s):  
Austin J. Hurst ◽  
Michael A. Lawrence ◽  
Raymond M. Klein
Keyword(s):  
Spatial Attention ◽  
Mixed Model ◽  
Stimulus Onset ◽  
Voluntary Attention ◽  
Colour Perception ◽  
Mixed Model Analysis ◽  
Continuous Response ◽  
Exogenous Cueing ◽  
Exogenous Cues ◽  
Onset Asynchrony

Existing research has found that spatial attention alters how various stimulus properties are perceived (e.g., luminance, saturation), but few have explored whether it improves the accuracy of perception. To address this question, we performed two experiments using modified Posner cueing tasks, wherein participants made speeded detection responses to peripheral colour targets and then indicated their perceived colours on a colour wheel. In E1, cues were central and endogenous (i.e., prompted voluntary attention) and the interval between cues and targets (stimulus onset asynchrony, or SOA) was always 800 ms. In E2, cues were peripheral and exogenous (i.e., captured attention involuntarily) and the SOA varied between short (100 ms) and long (800 ms). A Bayesian mixed-model analysis was used to isolate the effects of attention on the probability and the fidelity of colour encoding. Both endogenous and short-SOA exogenous spatial cueing improved the probability of encoding the colour of targets. Improved fidelity of encoding was observed in the endogenous but not in the exogenous cueing paradigm. With exogenous cues, inhibition of return (IOR) was observed in both RT and probability at the long SOA. Overall, our findings reinforce the utility of continuous response variables in the research of attention.

scholarly journals How Does Fearful Emotion Affect Visual Attention?

2021 ◽  
Vol 11 ◽  
Author(s):  
Zhe Shang ◽  
Yingying Wang ◽  
Taiyong Bi
Keyword(s):  
Visual Acuity ◽  
Time Course ◽  
Stimulus Onset ◽  
Perceptual Sensitivity ◽  
Adaptive Responses ◽  
Cueing Task ◽  
Fearful Face ◽  
The Face ◽  
Emotional Attention ◽  
Onset Asynchrony

It has long been suggested that emotion, especially threatening emotion, facilitates early visual perception to promote adaptive responses to potential threats in the environment. Here, we tested whether and how fearful emotion affects the basic visual ability of visual acuity. An adapted Posner’s spatial cueing task was employed, with fearful and neutral faces as cues and a Vernier discrimination task as the probe. The time course of the emotional attention effect was examined by varying the stimulus onset asynchrony (SOA) of the cue and probe. Two independent experiments (Experiments 1 and 3) consistently demonstrated that the brief presentation of a fearful face increased visual acuity at its location. The facilitation of perceptual sensitivity was detected at an SOA around 300 ms when the face cues were presented for both 250 ms (Experiment 1) and 150 ms (Experiment 3). This effect cannot be explained by physical differences between the fearful and neutral faces because no improvement was found when the faces were presented inverted (Experiment 2). In the last experiment (Experiment 4), the face cues were flashed very briefly (17 ms), and we did not find any improvement induced by the fearful face. Overall, we provide evidence that emotion interacts with attention to affect basic visual functions.

scholarly journals Masking within and across visual dimensions: Psychophysical evidence for perceptual segregation of color and motion

2011 ◽  
Vol 28 (5) ◽  
pp. 445-451 ◽  
Author(s):  
SAMUEL W. CHEADLE ◽  
SEMIR ZEKI
Keyword(s):  
Neural Coding ◽  
Time Course ◽  
Visual Masking ◽  
Processing System ◽  
Stimulus Onset ◽  
Feature Interaction ◽  
Color Target ◽  
Color Processing ◽  
Visual Attribute ◽  
Onset Asynchrony

AbstractVisual masking can result from the interference of perceptual signals. According to the principle of functional specialization, interference should be greatest when signal and mask belong to the same visual attribute (e.g., color or motion) and least when they belong to different ones. We provide evidence to support this view and show that the time course of masking is visual attribute specific. First, we show that a color target is masked most effectively by color (homogeneous target-mask pair) and least effectively by motion (heterogeneous pair) and vice versa for a motion target. Second, we show that the time at which the mask is most effective depends strongly on the target-mask pairing. Heterogeneous masking is strongest when the mask is presented before the target (forward masking) but this is not true of homogeneous masking. This finding supports a delayed cross-feature interaction due to segregated processing sites. Third, lengthening the stimulus onset asynchrony between target and mask leads to a faster improvement in color than in motion detectability, lending support for a faster color processing system and consistent with reports of perceptual asynchrony in vision. In summary, we present three lines of psychophysical evidence, all of which support a segregated neural coding scheme for color and motion in the human brain.

The Time Course of Response Activation with Dangerous Objects

2018 ◽  
Vol 21 ◽  
Author(s):  
Liang Zhao
Keyword(s):  
Mental Representation ◽  
Congruency Effect ◽  
Motor System ◽  
Time Course ◽  
Stimulus Onset ◽  
Visual Object ◽  
Dangerous Object ◽  
Priming Paradigm ◽  
Onset Asynchrony ◽  
Response Activation

AbstractThe action property of an object appears to function as an intrinsic part of its mental representation. This phenomenon has been demonstrated in cases where although the grasp response evoked by a visual object is irrelevant to a participant’s task it still appears to be encoded. This is an affordance effect. Recent findings have shown that dangerous objects can modulate the motor system by evoking aversive affordances. However, the way the time course of response activation generated by the dangerous object develops remains unclear. To investigate this process, we used a priming paradigm that varied the stimulus-onset asynchrony (SOA) between a prime and a target. Participants were asked to judge a symbol after presentation of a dangerous object. Results showed a significant congruency effect between the affordance of the ignored object and the requisite response when the SOA was 800 and 1,200 ms, (t(29) = 4.13, p < .001; t(29) = 2.56, p < .05, respectively). However, with briefer SOAs (0 and 400 ms), this congruency effect was not observed (ps > .10). Results indicate the time course of response activation with a dangerous object are relatively long-lasting.

Sign in / Sign up

Export Citation Format

Share Document