Effects of display luminance, stimulus meaningfulness, and probe duration on visible and schematic persistence.

1991 ◽  
Vol 45 (1) ◽  
pp. 54-74 ◽  
Author(s):  
Peter Dixon ◽  
Vincent Di Lollo
Keyword(s):  
Stimulus Meaningfulness ◽  
Luminance Stimulus

Foveal Attention Modulates Responses to Peripheral Stimuli

2000 ◽  
Vol 83 (4) ◽  
pp. 2443-2452 ◽  
Author(s):  
Simo Vanni ◽  
Kimmo Uutela
Keyword(s):  
Visual Field ◽  
Target Location ◽  
Peripheral Vision ◽  
Human Subjects ◽  
Stimulus Onset ◽  
Visual Object ◽  
Frontal Eye Field ◽  
L1 Norm ◽  
Luminance Stimulus ◽  
The Right

When attending to a visual object, peripheral stimuli must be monitored for appropriate redirection of attention and gaze. Earlier work has revealed precentral and posterior parietal activation when attention has been directed to peripheral vision. We wanted to find out whether similar cortical areas are active when stimuli are presented in nonattended regions of the visual field. The timing and distribution of neuromagnetic responses to a peripheral luminance stimulus were studied in human subjects with and without attention to fixation. Cortical current distribution was analyzed with a minimum L1-norm estimate. Attention enhanced responses 100–160 ms after the stimulus onset in the right precentral cortex, close to the known location of the right frontal eye field. In subjects whose right precentral region was not distinctly active before 160 ms, focused attention commonly enhanced right inferior parietal responses between 180 and 240 ms, whereas in the subjects with clear earlier precentral response no parietal enhancement was detected. In control studies both attended and nonattended stimuli in the peripheral visual field evoked the right precentral response, whereas during auditory attention the visual stimuli failed to evoke such response. These results show that during focused visual attention the right precentral cortex is sensitive to stimuli in all parts of the visual field. A rapid response suggests bypassing of elaborate analysis of stimulus features, possibly to encode target location for a saccade or redirection of attention. In addition, load for frontal and parietal nodi of the attentional network seem to vary between individuals.

Transfer of Paired-Associates as a Function of Stimulus Meaningfulness

1978 ◽  
Vol 42 (1) ◽  
pp. 255-257
Author(s):  
Marla Kahn-Edrington ◽  
Coleman Merryman ◽  
Shelli Helm ◽  
Gary Okowita
Keyword(s):  
Paired Associate ◽  
Paired Associates ◽  
Stimulus Meaningfulness

Paired-associate transfer in the A-D, A-B paradigm was negative for stimuli of high meaningfulness but not for stimuli of low meaningfulness. This result is consistent with Martin's hypothesis of variable encoding.

The Effect of Stimulus Meaningfulness on the Formation of Equivalence Classes

2000 ◽  
Vol 1 (2) ◽  
pp. 71-87 ◽  
Author(s):  
Fiona Lyddy ◽  
Dermot Barnes-Holmes ◽  
Peter J. Hampson
Keyword(s):  
Equivalence Classes ◽  
Stimulus Meaningfulness

Speed Discrimination in Luminance and Colour Stimuli as a Function of Contrast

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 49-49
Author(s):  
S M Wuerger ◽  
A H Morgan
Keyword(s):  
Carrier Frequency ◽  
Standard Stimulus ◽  
Consistent Difference ◽  
Adaptive Procedure ◽  
Gabor Function ◽  
Moving Stimulus ◽  
Measured Speed ◽  
Speed Discrimination ◽  
Luminance Stimulus ◽  
Perceived Speed

We measured speed discrimination for isoluminant red - green and luminance-defined moving stimuli. The horizontal profile of the stimuli was a Gabor function with a carrier frequency of 2 cycles deg−1. The standard stimulus was a luminance stimulus with a fixed speed of 2 deg s−1 and a fixed contrast of 0.1. The comparison stimuli were either luminance stimuli (cone contrasts: 0.05, 0.1, 0.2, 0.4) or chromatic stimuli (cone contrasts: 0.025, 0.05, 0.1). The speed of the comparison stimuli was varied by an adaptive procedure. After each trial the observer indicated which of the 2 intervals contained the slower moving stimulus. The stimuli always moved horizontally and the direction was chosen randomly at each trial. The main findings were: (i) For luminance stimuli, the perceived speed was independent of contrast (ranging from 0.1 to 0.4). For colour stimuli, the perceived speed increased with contrast for two out of four observers. (ii) The sensitivity for speed discrimination was independent of contrast for luminance and for colour stimuli. (iii) There was no consistent difference in speed discrimination sensitivity between colour and luminance stimuli when the stimuli were equated in cone contrast.

Stimulus meaningfulness and unlearning in the A-B, A-C transfer paradigm.

1966 ◽  
Vol 71 (6) ◽  
pp. 917-920 ◽  
Author(s):  
Joseph A. Bryk ◽  
Donald H. Kausler
Keyword(s):  
Stimulus Meaningfulness ◽  
Transfer Paradigm

Primate Pupillary Light Reflex: Receptive Field Characteristics of Pretectal Luminance Neurons

2003 ◽  
Vol 89 (6) ◽  
pp. 3168-3178 ◽  
Author(s):  
Robert J. Clarke ◽  
Hongyu Zhang ◽  
Paul D. R. Gamlin
Keyword(s):  
Receptive Fields ◽  
Pupillary Light Reflex ◽  
Central Visual Field ◽  
Light Reflex ◽  
Pupillary Light ◽  
Pupillary Responses ◽  
Retinal Input ◽  
Pretectal Nucleus ◽  
Luminance Stimulus ◽  
Olivary Nucleus

This study examined the response properties of luminance neurons found within the pretectal olivary nucleus (PON), which is the pretectal nucleus that mediates the primate pupillary light reflex. We recorded the activity of 121 single units in alert, behaving rhesus monkeys trained to fixate a back-projected laser spot while a luminance stimulus was presented. The change in the firing rate of luminance neurons was measured as a function of changes in the size, retinal illuminance, and position of the stimulus. We found that these neurons possessed large receptive fields, which were sufficiently distinct that they could be placed into three classes. Approximately 40% of the PON luminance neurons responded well to stimuli presented in either the contralateral or ipsilateral hemifield. These neurons were classified as “bilateral” neurons. In the primate, retinal projections to the pretectum and other retinorecipient nuclei are organized such that direct retinal input can only account for the contralateral hemifield responses of these neurons. Thus the representation of the ipsilateral hemifield in “bilateral” PON cells must result from input from a nonretinal source. Approximately 30% of PON neurons responded only to stimuli presented in the contralateral hemifield. These neurons were classified as “contralateral” neurons. Finally, approximately 30% of PON neurons responded to stimuli presented at or near the animal's fixation point. These neurons were classified as “macular” neurons. The mean firing rates of all classes of neurons increased with increases in stimulus size and luminance within their receptive fields. The thresholds and magnitude of these responses closely matched those that would be appropriate for mediating the pupillary light reflex. In summary, these results suggest that all three classes of PON neurons contribute to the behaviorally observed pupillomotor field characteristics in which stimuli at the macular produce substantially larger pupillary responses than more peripheral stimuli. The contributions of “bilateral” and “contralateral” cells account for pupillary responses evoked by peripheral changes in luminance, whereas the contributions of all three cell classes account for the larger pupillary responses evoked by stimuli in the central visual field.

An Experimental Study on the Luminance Perception of Lighting Environment

2011 ◽  
Vol 250-253 ◽  
pp. 3159-3162
Author(s):  
Li Ye Sun ◽  
Gang Liu ◽  
Hong Hai
Keyword(s):  
Experimental Study ◽  
Theoretical Basis ◽  
Subjective Evaluation ◽  
Psychological Factor ◽  
Qualitative Description ◽  
Quantitative Index ◽  
Low Luminance ◽  
Quantification Analysis ◽  
Lighting Environment ◽  
Luminance Stimulus

Considering the characteristics of vision in the low luminance and weak contrast environment, this research obtains a series of simulant scenes. By means of experiment observation, quantification analysis and subjective evaluation, this research proposes a kind of scientific and controllable methods and modes, then relates the quantitative index and the qualitative description in order to take physics and psychological factor into the comprehensive consideration in lighting environment. Finally, it obtains the scope of luminance stimulus and the quantification relations. The results of this research can provide theoretical basis, model and quantitative suggests for corresponding standards. It has significance to urban lighting planning, design and management.

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