scholarly journals Effects of stimulus range on color categorization

2011 ◽  
pp. 265-276 ◽  
Author(s):  
Oliver Wright
Keyword(s):  
Stimulus Range ◽  
Color Categorization

Magnitude Estimation and Cross-Modal Matching of Lingual Vibrotactile and Auditory Sensation

1989 ◽  
Vol 32 (3) ◽  
pp. 698-702 ◽  
Author(s):  
Daniel Harris ◽  
Donald Fucci ◽  
Linda Petrosino
Keyword(s):  
Auditory Stimulus ◽  
Magnitude Estimation ◽  
Sensory Processing ◽  
Test Site ◽  
Systematic Investigation ◽  
Thenar Eminence ◽  
Stimulus Range ◽  
Psychophysical Scaling ◽  
Scaling Methods ◽  
Response Biases

The present experiment was a preliminary attempt to use the psychophysical scaling methods of magnitude estimation and cross-modal matching to investigate suprathreshold judgments of lingual vibrotactile and auditory sensation magnitudes for 20 normal young adult subjects. A 250-Hz lingual vibrotactile stimulus and a 1000-Hz binaural auditory stimulus were employed. To obtain judgments for nonoral vibrotactile sensory magnitudes, the thenar eminence of the hand was also employed as a test site for 5 additional subjects. Eight stimulus intensities were presented during all experimental tasks. The results showed that the slopes of the log-log vibrotactile magnitude estimation functions decreased at higher stimulus intensity levels for both test sites. Auditory magnitude estimation functions were relatively constant throughout the stimulus range. Cross-modal matching functions for the two stimuli generally agreed with functions predicted from the magnitude estimation data, except when subjects adjusted vibration on the tongue to match auditory stimulus intensities. The results suggested that the methods of magnitude estimation and cross-modal matching may be useful for studying sensory processing in the speech production system. However, systematic investigation of response biases associated with vibrotactile-auditory psychophysical scaling tasks appears to be a prerequisite.

scholarly journals Properties of Shape Tuning of Macaque Inferior Temporal Neurons Examined Using Rapid Serial Visual Presentation

2007 ◽  
Vol 97 (4) ◽  
pp. 2900-2916 ◽  
Author(s):  
Wouter De Baene ◽  
Elsie Premereur ◽  
Rufin Vogels
Keyword(s):  
Rapid Serial Visual Presentation ◽  
Population Analysis ◽  
Visual Presentation ◽  
Stimulus Range ◽  
High Rate ◽  
Neuronal Responses ◽  
Standard Testing ◽  
Complex Shapes ◽  
Shape Tuning ◽  
Ordinal Level

We used rapid serial visual presentation (RSVP) to examine the tuning of macaque inferior temporal cortical (IT) neurons to five sets of 25 shapes each that varied systematically along predefined shape dimensions. A comparison of the RSVP technique using 100-ms presentations with that using a longer duration showed that shape preference can be determined with RSVP. Using relatively complex shapes that vary along relatively simple shape dimensions, we found that the large majority of neurons preferred extremes of the shape configuration, extending the results of a previous study using simpler shapes and a standard testing paradigm. A population analysis of the neuronal responses demonstrated that, in general, IT neurons can represent the similarities among the shapes at an ordinal level, extending a previous study that used a smaller number of shapes and a categorization task. However, the same analysis showed that IT neurons do not faithfully represent the physical similarities among the shapes. The responses to the two-part shapes could be predicted, virtually perfectly, from the average of the responses to the respective two parts presented in isolation. We also showed that IT neurons adapt to the stimulus distribution statistics. The neural shape discrimination improved when a shape set with a narrower stimulus range was presented, suggesting that the tuning of IT neurons is not static but adapts to the stimulus distribution statistics, at least when stimulated at a high rate with a restricted set of stimuli.

1.2 Method of constant stimuli (Method of frequency) By the Method of Frequency the stimulus range is selected in discrete intervals so that the frequency of positive answers is distributed over the range between 1% and 99%. In general, the frequency of positive res­ ponses either for an individual or for a group, is cumulatively normally distributed over a geometric intensity continuum. The absolute odor thre­ shold can then be defined as the effective dose corresponding to an arbi­ trarily selected frequency of positive responses, ordinarily 50% : ED^: Effective dose at the 50% level. 3.1.3 Signal detection The Signal Detection principle is a determination of the relation­ ship between hits and false alarms. In determining signal detectability, a stimulus or a few stimuli are presented in random order, alternating with noise. Since sensory impressions resulting frcm the presentation of stimulus versus noise are assumed to be normally distributed over the same intensity continuum and to have the same dispersion, the index of detectability d' for p (hits) minus p (false) indicates the extent to which the two distributions overlap. 3.2 Indication of response 3.2.1 "Yes" or "no" response In the classical evaluation yes-no answers are dependent on the sub­ jects1 honesty and motivation among other factors. However, yes-no ans­ wers may be evaluated if they are presented a sufficiently large number of times alternating with blanks. 3.2.2 forced choice technique One method of controlling response perseveration and otter antici­ pation factors is to use a forced choice response indication based on two or more response categories. In the measurement of odors the panelist has to report the temporal position of positive stimuli in a series of randan blanks. If the concentration is below the threshold, the test sub­ jects will guess. As the odorant concentration will increase, the rela­ tive cumulative frequency for identification of the correct sample will be greater. In order to determine the relative odor recognition a cor­ rection must be made. 3.3 Size of stimulus intervals 3.3.1 Concentration intervals In selecting the stimulus continuum in threshold determination, the relation between just noticeable difference in relation to the intensity of stimuli is of interest. In accordance with Weber's law this quotient is assumed to be a constant. Therefore it would appear best to determine absolute thresholds on an intensity continuum in the form of a gecxnetric progression. 3.2.2 Time intervals Because of adaptation processes the exposure time until reaching a decision should be limited. Also the interval between two stimuli must be observed.

1986 ◽  
pp. 71-71
Keyword(s):  
Signal Detection ◽  
Effective Dose ◽  
Random Order ◽  
Stimulus Range ◽  
Forced Choice ◽  
Just Noticeable Difference ◽  
False Alarms ◽  
Choice Response ◽  
Temporal Position ◽  
Normally Distributed

Attention, Stimulus Range, and Identification of Loudness

2019 ◽  
pp. 3-25
Author(s):  
R. Duncan Luce ◽  
Robert M. Nosofsky
Keyword(s):  
Stimulus Range
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