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Questions tagged [psychophysics]

For questions about the quantitative study of varying a stimulus's properties to observe the effect on sensation (and perception)

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24 views

Comparing psychometric curves of two different tasks

I ran two different tasks on subjects, and fit psychometric curves to the results of 10 stimulus levels for each task. Each psychometric curve was defined by a slope and a bias, i.e. point of ...
2
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1answer
21 views

How to control subject's response bias in 2-interval force choice task

I am using a two-interval force choice (2IFC) task to estimate detection threshold and choose an appropriate signal level for my following experiment, by estimating sensitivity ($d'$) for each signal ...
3
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0answers
39 views

Solving for HR and FAR, given ACC and C

Lets say I have an equal variance SDT framework with an equal number of target present and target absent trials: $d'=Z^{-1}(HR)-Z^{-1}(FAR)$ $C=\frac{Z^{-1}(HR)+Z^{-1}(FAR)}{-2}$ $ACC=\frac{HR+(1-...
5
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1answer
39 views

Visual field testing: Choose between Yes/No, 2AFC, and 2IFC task?

As a newbie to psychophysics experiment, I have a small project to do visual field testing on healthy, adult, naive subjects. The experiment stimulus is a small sine grating (0.3 degree, 6 cycles/...
3
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1answer
115 views

Finding largest level of imperceptible noise in an image

Suppose that we want to find the "largest level" of a random noise that can safely be added to an image such that the resultant noisy image cannot be distinguishable from the original noise-free image....
2
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1answer
42 views

Why do errors such as typos happen?

Why do typos happen? Why do we sometimes type the same word right, and sometimes wrong? For the same reason, why does a player of Flappy Bird for instance crash at pipe 138? Why not any of the 137 ...
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1answer
38 views

How to use QUEST in a discrimination task

Similar to the question "How to use a QUEST staircase in 2-AFC”. I also have a question about using QUEST. In fact, I too tried to find an answer in Psychophysics: A Practical Introduction by Kingdom ...
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1answer
30 views

What's the best way to calculate an index score based on reaction time, variance and accuracy?

Say I have a go/no-go task and my output data includes 3 parameters: average reaction time, variance of reaction time, and number of errors. I want to composite all of the parameters into a single ...
4
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2answers
61 views

Reason for Inter-stimulus-Interval in psychology studies

In many of the studies that I have read or participated in, I have seen that they show a blank screen between two stimuli. For example, in a study by Cohen et al. (2017), a training paradigm was used ...
3
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0answers
75 views

PSE with Palamedes or Psignifit

I have used a Cumulative Gaussian function to fit the data I got from a 2AFC experiment. How can I calculate the point of subjective equality using the Palamedes toolbox for matlab or the psignifit ...
3
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2answers
66 views

How are people working in psychophysics trained?

It is unclear to me how people in psychophysics are trained. Are they psychologists, or physicists, or physicians, or biologists, or physiologists? Or can they be any of those? What if someone doing ...
5
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2answers
74 views

What are the benefits of giving feedback to subjects during a discrimination task?

Context I am planning an experiment where the subjects would need to determine the language of the stimulus after listening to it once, given two alternatives, L1 or L2. In total I have 500 trials ...
7
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1answer
244 views

In the digit span test, why do some strategies work and others don't?

I got a free copy of PEBL, psych experiment software, which includes a couple of standard working memory tests. When I perform the digit span working memory test, I can repeat the numbers as they ...
3
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0answers
41 views

How bright must a light bulb to be noticed in a room?

If one has say an 800 lumen bulb, how many lux are necessary in order for a human to detect when it's suddenly turned on in a room with brightness levels of 30 Lux 50 Lux 100 Lux 1.-How many Lux ...
7
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2answers
117 views

Accuracy of psychopy keystroke duration measurement

I am using Psychopy and this code for measuring keystroke duration as suggested in this answer for my previous question: ...
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0answers
27 views

Calculating chance behavior and behavioral strategies in delayed response paradigm [closed]

I am looking for more thoughts on appropriate ways of calculating chance behavior and subsequently calculating behavioral strategies for the following two types of tasks. Both have two types of errors ...
5
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1answer
104 views

Calculate threshold from 'binary' yes/no data

For various reasons, I have a crappy experimental design that I am forced to deal with. I present subjects with 20 yes/no trials, out of which 5 are no-signal catch trials and 15 are signal trials. ...
5
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3answers
712 views

How to use a QUEST staircase in 2-AFC?

Firstly, I need to declare that I am not psychologyst, however I am currently working on visual recognition research. To be precise, I working on face recognition deficits in Autism Spectrum Disorder. ...
3
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1answer
1k views

How to measure and quantify concentration or focus?

How can we measure and quantify concentration or focus? For example, if I were to say: "If you do Activity X while using Y, you will be more concentrated than if you were using Z" How can I ...
4
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1answer
63 views

Understanding a negative correlation between Pc and signal strength

When I present two signals in paired comparison and ask the respondent to select the stronger signal in the pair, I find that it is the signal strength of the second signal that more so determines ...
8
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3answers
232 views

Freeware for measuring keystroke duration

I am searching for freeware to measure the duration of a keystroke or mouse-click, both would work. Does anyone have an idea? Matlab toolboxes are, unfortunately, of no use to me.
4
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2answers
76 views

How to specify the quickest movement a human can do based on MTM standards?

I am looking for a benchmark as a reference regarding the human Kinesiology that specifies the quickest movement a human can do on basic everyday movements like computer mouse clicking. As far as I ...
6
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1answer
61 views

Where can I find experimental data supportive of the Hick-Hyman law?

The Hick-Hyman law states that in a reaction-time experiment, the average reaction time of a human subject is a linear function of the average information $\sum -p \log p$, i.e. the entropy, contained ...
5
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1answer
166 views

At what time in a psychophysical test are catch trials preferably presented?

I am designing a tone-in-noise detection task (specifically a high frequency N0Spi task). For various reasons I need to use a yes-no paradigm and the method of constant stimuli. I am severely limited ...
3
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1answer
190 views

How to fit averaged data to obtain a single psychometric function?

I have psycho-physical data from a motion discrimination task in order to obtain PSE (point of subjective equality). I am using psignifit and have constructed individual psychometric logistic ...
4
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1answer
62 views

Timing accuracies for displaying frames and recording response times?

There are a few open-sources tools available to run psychology experiments. However, some are working in a browser. Do we know how precisely they can record response times? Also, can we present a ...
4
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1answer
482 views

What are the advantages of 2AFC in a psychophysical discrimination task?

As far as I understand. In the task of Two alternative forced choice (2AFC), given two possible stimuli, $S1$ or $S2$, the subject has to decide weather he\she (it) saw the sequence $(S1,S2)$ or the ...
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1answer
147 views

Does training affect the tactile oblique effect?

In the visual sciences it is known that the oblique effect can be reduced by means of training. The oblique effect is observed when testing subjects psychophysically with a grating acuity task (e.g., ...
4
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1answer
253 views

Where can I obtain a button box for reaction-time measurements under a Windows OS?

I need a button box / response box to hook up with a laptop computer and Windows Operating System for a reaction time study. A simple box will suffice and I do not need more than two buttons. I need a ...
6
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1answer
121 views

Why so few subjects in psychophysics?

Why is it that most psychophysics experiments only use a handful of subjects (typically around five, but sometimes even four, three or two), whereas the "norm" for experimental psychology (assuming a ...
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1answer
501 views

Signal detection theory: How to calculate c' when d' is 0?

Reframed the original question to include more background information: My experiment concerns the recall ability of individuals concerning information about animals. Within-subject design: Whether an ...
8
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1answer
159 views

Applying signal detection theory to single-stimulus presentations

Normally, signal detection theory (SDT) is applied to data that involves giving two-alternative forced choice (2AFC) responses to pairs of stimuli, for instance saying whether stimulus B was the same ...
3
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1answer
27 views

Does work exist on relative valuations versus numeric valuations?

I've been trying to use Google Scholar to find something on this issue, but I fear I may not have found anything due to using incorrect terms. I am looking for any work which looks at rating systems ...
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1answer
47 views

Does color constancy overestimate?

Consider I have a few references from white to yellowish, and I look at them in 2 different lights: a cool-coloured light (white/~6500k) and a warm-coloured light (yellow/~3500k). Firstly, intuitively,...
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1answer
444 views

How can I fit a psychometric function such that the minimum is 50% (chance level)?

I have data from the behavioral component of an fMRI study in which subjects are asked to perform a 2AFC discrimination task with targets at variable contrast. That is, a target will be presented at ...
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0answers
29 views

Quest procedure convergence after random answers

I use Quest procedure to find threshold for stereo disparity changes of a stimuli. I use a C++ implementation derived from the one in Psychotoolbox and I wonder whether the behaviour I observe is ...
5
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3answers
189 views

Recent psychophysical studies using the “Method of Adjustment”?

The Method of Adjustment, devised by G.T. Fechner, is one of the three classical psychophysical procedures used to examine perceptual performance. It came to fame through early studies of visual ...
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1answer
306 views

Quantifying chromatic adaptations made by the brain

What are the ways one can use to measure the kind of adaptations done by the brain to provide colour constancy? Has this been done before?
6
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1answer
214 views

In psychophysics, why are log luminance rather than absolute luminance values reported?

Are there any papers which justify converting into log luminance? For example papers showing humans being sensitive to changes in log luminance rather than luminance per se?
13
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1answer
382 views

Are staircases more efficient than the method of constant stimuli?

A Bayesian Quest adaptive procedure (Watson and Pelli 1983) is the theoretically most efficient procedure for estimating thresholds under a certain, potentially unrealistic, set of constraints. In my ...
5
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1answer
496 views

Do unequal step sizes in staircase procedure affect the convergence?

Consider a psychophysics procedure using a standard staircase method to adaptively find the threshold, using a 2AFC paradigm and a 1-up, 3-down method to determine the 75% threshold. Now suppose the ...
4
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1answer
203 views

Optimal number of dimensions in multidimensional scaling

I have run an experiment on consonance-dissonance evaluation of musical intervals on 40 individuals using all the possible intervals from 3 registers (plus their inversions), and I want to apply a ...
2
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1answer
456 views

What hardware setup is commonly used for low-latency audio stimulation?

I need to carefully control the latency and timing of auditory stimulation in an upcoming experiment. Some of this depends on software, but my question is specifically relating to hardware, drivers ...
3
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1answer
314 views

How can I design a staircase function that converges on a given hit-rate?

I'm in the process of creating a simple contrast staircase function where subjects are initially presented with high-contrast Gabor patches and are subsequently queried as to their orientation in a ...
4
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1answer
6k views

Two different values for criterion in signal detection theory?

I'm a signal detection theory newbie. I have data with a classical SDT design: the participants can answer YES or NO to a question where the correct answer is YES or NO, depending on the presence or ...
4
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2answers
467 views

Which physical properties of a stimulus can a human attend to?

I am not only curious about speech, but for concreteness in illustrating my question, I consider the case of speech perception. Assume a listener is presented with an acoustic waveform. The wave ...
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1answer
215 views

How to set up a binocular rivalry experiment which splits a single image in two separately controlled ones?

The question is about the actual physical setup and steps needed to take in order to experiment with the phenomena. I found a tutorial on jove.com, "How to Create and Use Binocular Rivalry", and it ...
5
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4answers
154 views

Introductory material on psychophysics with a focus on visual stimuli

Is there any introductory-level material available on psychophysics that you can recommend to someone without a background in cognitive sciences? Visual stimuli is the main area of interest. Edit: ...
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3answers
1k views

Math or Physics: Which is the more relevant background to enter Cognitive Sciences and Psychology? [closed]

What would be a more suitable background to enter cognitive sciences, mathematical psychology, and study of emotions? I have the option of taking a Integrated Masters Degree in Mathematical Sciences, ...
5
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2answers
1k views

Minimum duration for presenting a visual stimulus on screen

My experiment involves presenting simple visual stimuli briefly on screen (200 ms to 1000 ms). The stimuli would be simple enough (e.g. a circle and a line) but I want to use a range of durations to ...