scholarly journals Object Recognition’s Garden Path: Low Spatial Frequencies

2020 ◽  
Author(s):  
JOHN ROHRLICH ◽  
Tsung-Ren Huang ◽  
Thomas E. Hazy ◽  
Randall C. O'Reilly
Keyword(s):  
Significant Delay ◽  
Top Down ◽  
Wrong Answer ◽  
Garden Path ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Blurred Image ◽  
Delayed Recognition ◽  
Cortical Influence ◽  
Competitive Activation

Several experiments, notably one done by Bruner and Potter (1964), have demonstrated delayed object recognition when viewing a blurred image gradually come into focus. Bruner and Potter (1964) suggested that the wrong answer is held until there is an obvious contradiction. Others have hypothesized that “competitive activation” is responsible for delayed recognition. The results of the experiments reported in this paper are consistent with a third hypothesis, that delayed recognition is due to an initial organization of image elements that is incompatible with correct recognition and that the initial grouping and figure-ground perception, among other aspects of organization, drive subsequent perception via top-down cortical pathways. A total of 7 experiments using 3 forms of degradation supported this hypothesis. Images degraded by low-pass filtering produced significant delay in recognition, while degradation by fragmentation did not, and a third form of degradation similar to fragmentation mitigated the effect. The experiments also demonstrate that if images are low-pass filtered delayed recognition occurs with presentations of as little as 100 ms and early presentations lead to delayed recognition over long intertrial intervals, at least 105 seconds. Further, support for the hypothesis that top-down cortical influence is key to this phenomenon came from an experiment showing that masking eliminates delayed recognition for short presentations. Taken together these results support a hypothesis that delayed recognition is due to errors in perceptual organization that lead to incorrect responses and these errors are fostered by low spatial frequencies.

Utilisation d'une ligne de microphotodiodes en spectroscopie dispersive : application à la détection du NO2

1983 ◽  
Vol 61 (2) ◽  
pp. 301-304 ◽  
Author(s):  
Jacques Bures ◽  
François Leonard ◽  
Jean-Pierre Monchalin
Keyword(s):  
Absorption Spectrum ◽  
Systematic Errors ◽  
Sufficient Information ◽  
Atmospheric Pollutant ◽  
Spatial Frequencies ◽  
Low Pass ◽  
On Line ◽  
Photodiode Array ◽  
Analysis System

A self-scanned photodiode array has been used as a multiplex sensor for laboratory detection and measurement, by dispersive spectroscopy, of trace quantities of the atmospheric pollutant NO2. The on-line data acquisition and numerical analysis system allows in particular to eliminate some systematic errors and drifts (Taylor filtering) and the noise associated with high spatial frequencies (low-pass filtering). We have then been able to show that an absorption spectrum, corresponding to low absorber concentrations, has a sufficient information content for the characterization of the pollutant and the measurement of its concentration (ppm m), even when noise and drifts are present. The proposed system can be favorably compared to the ones, based on a single photoelectric detector, which are commercially used.

Top-Down versus Bottom-up Control of Saccades in Texture Perception

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 162-162 ◽  
Author(s):  
R Groner ◽  
A von Mühlenen ◽  
M Groner
Keyword(s):  
Eye Movements ◽  
Spatial Frequency ◽  
Target Stimulus ◽  
Saccadic Eye Movements ◽  
Landing Site ◽  
Luminance Contrast ◽  
Eye Tracker ◽  
Top Down ◽  
Bottom Up ◽  
Low Pass

An experiment was conducted to examine the influence of luminance, contrast, and spatial frequency content on saccadic eye movements. 112 pictures of natural textures from Brodatz were low-pass filtered (0.04 – 0.76 cycles deg−1) and high-pass filtered (1.91 – 19.56 cycles deg−1) and varied in luminance (low and high) and contrast (low and high), resulting in eight images per texture. Circular clippings of the central parts of the images (approximately 15% of the whole image) were used as stimuli. In the condition of bottom - up processing, the eight stimuli derived from one texture were presented for 1500 ms in a circular arrangement around the fixation cross. They were followed by a briefly presented target stimulus in the centre, which in half the trials was identical to one of the eight test stimuli. Participants had to decide whether the target stimulus was identical to any of the preceding stimuli. During a trial, their eye movements were recorded by means of a Dual-Purkinje-Image eye tracker. In the top - down condition, the target stimulus was presented in each trial prior to the display of the test stimulus. It was assumed that the priming with a target produced a top - down processing of the test stimuli. The latency and landing site of the first saccade were computed and compared between the top - down and bottom - up conditions. It is hypothesised that stimulus characteristics (luminance, contrast, and spatial frequency) play a more prominent role in bottom - up processing, while top - down processing is adjusted to the particular characteristics of the prime.

Temporal and Spatial Frequency Tuning of the Flicker Motion Aftereffect

Perception ◽  
1996 ◽  
Vol 25 (1_suppl) ◽  
pp. 12-12
Author(s):  
P J Bex ◽  
F A J Verstraten ◽  
I Mareschal
Keyword(s):  
Spatial Frequency ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Motion Aftereffect ◽  
Sine Wave ◽  
Test Grating ◽  
Spatial Frequency Tuning ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Sine Wave Gratings

The motion aftereffect (MAE) was used to study the temporal-frequency and spatial-frequency selectivity of the visual system at suprathreshold contrasts. Observers adapted to drifting sine-wave gratings of a range of spatial and temporal frequencies. The magnitude of the MAE induced by the adaptation was measured with counterphasing test gratings of a variety of spatial and temporal frequencies. Independently of the spatial or temporal frequency of the adapting grating, the largest MAE was found with slowly counterphasing test gratings (∼0.125 – 0.25 Hz). For slowly counterphasing test gratings (<∼2 Hz), the largest MAEs were found when the test grating was of similar spatial frequency to that of the adapting grating, even at very low spatial frequencies (0.125 cycle deg−1). However, such narrow spatial frequency tuning was lost when the temporal frequency of the test grating was increased. The data suggest that MAEs are dominated by a single, low-pass temporal-frequency mechanism and by a series of band-pass spatial-frequency mechanisms at low temporal frequencies. At higher test temporal frequencies, the loss of spatial-frequency tuning implicates separate mechanisms with broader spatial frequency tuning.

Spatial Integration of Objectively Equiluminous Chromatic Gratings

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 200-200
Author(s):  
M I Kankaanpää ◽  
J Rovamo ◽  
H T Kukkonen ◽  
J Hallikainen
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Spatial Integration ◽  
Chromatic Contrast ◽  
Shape Difference ◽  
Sensitivity Functions ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Chromatic Aberrations ◽  
Chromatic Contrast Sensitivity

Contrast sensitivity functions for achromatic and chromatic gratings tend to be band-pass and low-pass in shape, respectively. Our aim was to test whether spatial integration contributes to the shape difference found at low spatial frequencies. We measured binocular chromatic contrast sensitivity as a function of grating area for objectively equiluminous red - green and blue - yellow chromatic gratings. Chromatic contrast refers to the Michelson contrast of either of the two chromatic component gratings presented in counterphase against the combined background. Grating area ( A) varied from 1 to 256 square cycles ( Af2) at spatial frequencies ( f) of 0.125 – 4.0 cycles deg−1. We used only horizontal gratings at low and medium spatial frequencies to minimise the transverse and longitudinal chromatic aberrations due to ocular optics. At all spatial frequencies studied, chromatic contrast sensitivity increased with grating area. Ac was found to be constant at low spatial frequencies (0.125 – 0.5 cycles deg−1) but decreased in inverse proportion to increasing spatial frequency at 1 – 4 cycles deg−1. Thus, spatial integration depends similarly on spatial frequency for achromatic (Luntinen et al, 1995 Vision Research35 2339 – 2346) and chromatic gratings, and differences in spatial integration do not contribute to the shape difference of the respective contrast sensitivity functions.

Low Spatial Frequencies Dominate Apparent Motion

Perception ◽  
1983 ◽  
Vol 12 (4) ◽  
pp. 457-461 ◽  
Author(s):  
Vilayanur S Ramachandran ◽  
Arthur P Ginsburg ◽  
Stuart M Anstis
Keyword(s):  
Apparent Motion ◽  
Central Figure ◽  
Spatial Frequencies ◽  
Low Pass ◽  
High Pass

Experiments are reported which have been designed to establish what features of a pair of figures can be used as an input for apparent motion. The display consisted of a central figure, A, which appeared briefly and was followed immediately afterwards by two figures, B and C, which appeared on either side of the original location of A. Figure A can thus move towards either B or C. When A was a low-pass filtered square it moved towards C (a low-pass filtered square that was similar to A but ‘rotated’ by 45°) rather than towards B (a high-pass filtered square identical to A in orientation and size). When A was an unfiltered square it moved towards C (a low-pass filtered square of identical orientation) rather than towards B (a high-pass filtered square of identical orientation). Lastly, when A was a ‘solid’ square it moved towards C (a solid circle) rather than towards B (an outline square). All three experiments suggest that the direction of perceived movement is determined exclusively by low spatial frequencies rather than by similarity of oriented edges, especially when speed of alternation is rapid.

The Role of High Spatial Frequencies in Hemispheric Processing of Categorical and Coordinate Spatial Relations

2004 ◽  
Vol 16 (9) ◽  
pp. 1576-1582 ◽  
Author(s):  
Matia Okubo ◽  
Chikashi Michimata
Keyword(s):  
Visual Field ◽  
Spatial Frequency ◽  
Right Hemisphere ◽  
High Spatial Frequency ◽  
Spatial Relation ◽  
Spatial Relations ◽  
Right Visual Field ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Categorical Task

Right-handed participants performed categorical and coordinate spatial relation tasks on stimuli presented either to the left visual field-right hemisphere (LVF-RH) or to the right visual field-left hemisphere (RVF-LH). The stimuli were either unfiltered or low-pass filtered (i.e., devoid of high spatial frequency content). Consistent with previous studies, the unfiltered condition produced a significant RVF-LH advantage for the categorical task and an LVF-RH advantage for the coordinate task. Low-pass filtering eliminated this Task × Visual Field interaction; thus, the RVF-LH advantage disappeared for the categorical task. The present results suggest that processing of high spatial frequency contributes to the left hemispheric advantage for categorical spatial processing.

Temporal Characteristics of Top-Down Modulations during Working Memory Maintenance: An Event-related Potential Study of the N170 Component

2007 ◽  
Vol 19 (11) ◽  
pp. 1836-1844 ◽  
Author(s):  
Kartik K. Sreenivasan ◽  
Jennifer Katz ◽  
Amishi P. Jha
Keyword(s):  
Working Memory ◽  
Recognition Task ◽  
Event Related Potential ◽  
Perceptual Processing ◽  
Top Down ◽  
Domain Specific ◽  
N170 Component ◽  
Delay Duration ◽  
The Face ◽  
Delayed Recognition

We investigated the top-down influence of working memory (WM) maintenance on feedforward perceptual processing within occipito-temporal face processing structures. During event-related potential (ERP) recordings, subjects performed a delayed-recognition task requiring WM maintenance of faces or houses. The face-sensitive N170 component elicited by delay-spanning task-irrelevant grayscale noise probes was examined. If early feedforward perceptual activity is biased by maintenance requirements, the N170 ERP component elicited by probes should have a greater N170 amplitude response during face relative to house WM trials. Consistent with this prediction, N170 elicited by probes presented at the beginning, middle, and end of the delay interval was greater in amplitude during face relative to house WM. Thus, these results suggest that WM maintenance demands may modulate early feedforward perceptual processing for the entirety of the delay duration. We argue based on these results that temporally early biasing of domain-specific perceptual processing may be a critical mechanism by which WM maintenance is achieved.

scholarly journals Attention Modulates Electrophysiological Responses to Simultaneous Music and Language Syntax Processing

2019 ◽  
Author(s):  
Daniel J Lee ◽  
Harim Jung ◽  
Psyche Loui
Keyword(s):  
Cognitive Processing ◽  
Time Course ◽  
Syntactic Structure ◽  
Visual Presentation ◽  
Top Down ◽  
Garden Path ◽  
Music And Language ◽  
Electrophysiological Responses ◽  
Musical Syntax ◽  
Anterior Negativity

Music and language are hypothesized to share neural resources, particularly at the level of syntax processing. Recent reports suggest that attention modulates this sharing of neural resources, but the time-course of the effects of attention, and the degree to which attention operates similarly on music and language, are yet unclear. In this EEG study we manipulate the syntactic structure of simultaneously presented musical chord progressions and garden-path sentences in a modified rapid serial visual presentation paradigm, while varying top-down attentional demands to the two modalities. The Early Right Anterior Negativity (ERAN) was observed in response to both attended and unattended musical syntax violations. In contrast, an N400 was only observed in response to attended linguistic syntax violations, and a P3 only in response to attended musical syntax violations. Results show that top-down allocation of attention indeed affects the processing of syntax in both music and language, with different neural resources acting upon the two modalities particularly at later stages of cognitive processing. However, the processing of musical syntax at an earlier stage of the perceptual-cognitive pathway, as indexed by the ERAN, is partially automatic, and is strongly indicative of separate neural resources for music and language.

Spatial Content and Spatial Quantisation Effects in Face Recognition

Perception ◽  
1994 ◽  
Vol 23 (2) ◽  
pp. 129-146 ◽  
Author(s):  
Nicholas P Costen ◽  
Denis M Parker ◽  
Ian Craw
Keyword(s):  
Block Size ◽  
Noise Condition ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Critical Range ◽  
Face Images ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Gaussian Blurring ◽  
Speed And Accuracy

It has recently become apparent that if face images are degraded by spatial quantisation, or block averaging, there is a nonlinear acceleration of the decline in accuracy of recognition as block size increases. This suggests recognition requires a critical minimum range of object spatial frequencies. Two experiments were performed to clarify the phenomenon. In experiment 1, the speed and accuracy of recognition for six frontoparallel photographs of faces were measured. After familiarisation training sessions, the images were shown for 100 ms with 11, 21, and 42 pixels per face, horizontally measured. Transformations calculated to remove the same range of spatial frequencies were performed by means of quantisation, a Fourier low-pass filter, and Gaussian blurring. Although accuracy declined and speed increased in a significant, nonlinear manner in all cases as the image quality was reduced, it did so at a faster rate for the quantised images. In experiment 2, faces rated as being typical were shown at 9, 12, 23, and 45 pixels per face and with appropriate Fourier low-pass versions. The nonlinear decline was confirmed and it was shown that it could not be attributed to a ceiling effect. A further condition allowed quantised and Fourier low-pass conditions to be compared with an unstructured-noise condition of equal strength to that of the quantised images. These gave comparable, but slightly less impaired, recognition than the quantised images. It can be inferred from these results that the removal of a critical range of at least 8–16 cycles per face of information explains the step decline in recognition seen with quantised images. However, the decline found with quantised images is reinforced by internal masking from pixelisation.

The Importance of High Spatial Frequencies for Exogenous Consciousness. Evidence from the Attentional Blink Paradigm.

2019 ◽  
Author(s):  
Mickaël Jean Rémi Perrier ◽  
Louise Kauffmann ◽  
Carole Peyrin ◽  
Nicolas Vermeulen ◽  
Frederic Dutheil ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Attentional Blink ◽  
Crucial Role ◽  
Conscious Perception ◽  
Frequency Content ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Visual Consciousness ◽  
High Pass

We attempted to highlight the respective importance of low spatial frequencies (LSFs) and high spatial frequencies (HSFs) in the emergence of visual consciousness by using an attentional blink paradigm in order to manipulate the conscious report of visual stimuli. Thirty-eight participants were asked to identify and report two targets (happy faces) embedded in a rapid stream of distractors (angry faces). Conscious perception of the second target (T2) usually improved as the lag between the targets increased. The distractors between T1 and T2 were either non-filtered (broad spatial frequencies, BSF), low-pass filtered (LSF), or high-pass filtered (HSF). The spatial frequency content of the distractors resulted in a greater disturbance of T2 reporting in the HSF than in the LSF condition. We argue that this could support the idea of HSF information playing a crucial role in the emergence of exogenous consciousness in the visual system. Other interpretations are also discussed.

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