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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1 answer
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How to evaluate the convergence of a staircase?

I have a 2AFC staircase, with transformed up and down method (2up 1 down) or (2down 1 up), with equal step size (at the beginning there are higher step sizes, at the end there are the lower value). ...
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3 votes
1 answer
83 views

What are these extra 11 dimensions of human mind?

I posted this question on the physics stack exchange, but I was guided to ask the question here though from the view point of a neuro-scientist which should be more useful if she has already followed ...
0 votes
1 answer
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Why is threshold at 76% correct when d-prime = 1?

In signal detection theory using a 2-alternative forced choice task, when d' = 1, threshold is found at the stimulus intensity which is perceived 76% of the time (https://www.oxfordreference.com/view/...
3 votes
1 answer
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Are dedicated response boxes really better in precision than regular keyboards?

There are various (very pricey) commercial response boxes or pads (perhaps most notably Cedrus) that purportedly offer higher precision than regular keyboards. (Note that my question focuses on ...
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2 votes
0 answers
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Modeling psychophysical data: appropriate visualization to account for experimental design

Background information: I am modeling psychophysical data at the trial level for the first time. The data stem from a visual line bisection task with constant stimulus intensity, the response variable ...
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6 votes
1 answer
84 views

Different psychophysiological systems will turn on when dealing with things voluntary instead of involuntary

I heard somewhere that different psychophysiological systems will turn on when dealing with things voluntary instead of involuntary. If you compose a stressor on two groups of people. On one group ...
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0 votes
0 answers
27 views

What is the recommended way to deal with failed trials during an experiment run?

Imagine I run a psychophysical experiment. I have generated a sequence of trial conditions which are presented to each participant in same order. But not all of participants are equally good at ...
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1 vote
1 answer
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Slope of psychometric function too steep?

I am in a project where we are preparing a visual decision making experiment which requires participants to detect vertical grating in a patch of dynamic noise (the noise pattern is updated on every ...
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7 votes
5 answers
445 views

Which function to use for fitting learning curves?

Background I am fitting learning curves for cochlear implant (CI) users. These folks get a CI, and then need to start learning to understand speech again. They keep on improving for years. Along the ...
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2 votes
3 answers
107 views

What statistical tests should be performed to test effect of trials on response times where each subject has different number of data points?

I am running a behavioral experiment where a number of subjects (=20 in my case) perform a simple cognitive task. The experiment consists of a fixed number of trials (say, 40 in my case). During each ...
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3 votes
2 answers
73 views

Are there any definitions of the perception & JND of the colour of light approximately like how the Weber Law defines it for the brightness of light?

As I understand it, the greater light levels are the more we require in order to detect a difference. I've also read this holds true for colour saturation. However, I can't seem to find any ...
2 votes
1 answer
54 views

May somebody use oddball paradigm solely for psychophysical studies?

I'm an undergraduate linguistics student with a strong interest in cognitive psychology of visual attention. Nowadays, I'm studying on an undergraduate research project in which I'm planning to use ...
1 vote
1 answer
52 views

How to determine an unbiased estimate of threshold in a single-stimulus forced choice experiment?

Objective I need to estimate the unbiased threshold of detectable speed difference in a car-following task. The details are as follows: Experiment Design This experiment was performed in a driving ...
3 votes
2 answers
102 views

Why is deltaE not used as a measure of error?

I've recently read a few articles pertaining to visual memory. Most of them (e.g. Bays et al., 2009 use the continuous color recall task where they ask participants to recall the color of an object by ...
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3 votes
1 answer
47 views

Decrease in d' with concurrent increase of criterion

I was reading about an experimental condition where subjects d' (sensitivity) decreases, while at the same time their criterion is increasing (a shift to the right). The authors were arguing with a ...
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3 votes
1 answer
251 views

How to test whether THC or CBD gives a mental boost?

Studies have shown significant reduction in seizures in babies to adults when taking marijuana. I would call that amazing but what does it do in improving cognitive abilities in normal people? ...
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3 votes
2 answers
206 views

for a persistent perceptual experience, why is video able to have a lower frame rate than audio?

In film, images are typically shown to us at around 24 frames per second, but modern sound files will often have 44100 or 48000 samples per second. There's a threshold above ~12 fps where we will ...
3 votes
1 answer
241 views

Independence of criterion and d-prime (psychophysics)

I am reading here, page 5 that d' (d-prime) does not vary with criterion (in contrast to hit rate for instance which does vary with criterion, and which can be a biased measure of a subject's ...
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6 votes
1 answer
375 views

Understanding the concept behind d-prime

I know that sensitivity (d') is typically calculated as follows: d' = z(Hit Rates) - z (False Alarm Rates) I understand this as the idea is to standardize both distributions, and to then calculate ...
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3 votes
1 answer
247 views

Yes-No question in 2AFC staircase test

I understand the task of a 2AFC test is to select one of the two stimuli presented (e.g. the stronger one), whereas in Yes-No test there is only one stimulus presented. But is it ok to ask a Yes-No ...
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2 votes
1 answer
76 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 ...
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3 votes
1 answer
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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-...
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6 votes
1 answer
635 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/...
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3 votes
1 answer
144 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 votes
1 answer
189 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 ...
-1 votes
2 answers
231 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 ...
1 vote
1 answer
79 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 ...
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4 votes
2 answers
152 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 votes
0 answers
248 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 votes
2 answers
98 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 ...
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5 votes
2 answers
134 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 votes
1 answer
698 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 ...
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3 votes
0 answers
52 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 ...
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7 votes
2 answers
188 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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1 vote
0 answers
48 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 votes
1 answer
252 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. ...
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5 votes
3 answers
2k 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. ...
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4 votes
1 answer
10k 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 votes
1 answer
75 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 votes
3 answers
1k 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.
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3 votes
2 answers
99 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 ...
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5 votes
1 answer
93 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 ...
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4 votes
1 answer
430 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 ...
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4 votes
1 answer
472 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 votes
1 answer
75 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 votes
1 answer
1k 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 ...
6 votes
1 answer
181 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., ...
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4 votes
1 answer
756 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 ...
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5 votes
1 answer
184 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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10 votes
1 answer
764 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 ...
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