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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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Research and theories related to the physical form of Cognitive Fallacies

Is there any research about what physically happens inside our brain anatomically and neurologically when we humans commit cognitive fallacies (especially those fallacies documented in the book of ...
Piinhuann Chew's user avatar
1 vote
0 answers
12 views

gamma correcting a sinusoidal grating [psychophysics]

I am developing a stimulation setting wherre I present a sinusoidal grating to a subject. Because of the monitor gamma expansion by a factor of 2.2, I need to gamma compress my sinusoidal grating by a ...
André89's user avatar
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0 answers
18 views

QUEST Staircase Resolution and Accuracy

I am flickering letters on and off to participants, controlled by a flicker rate which I am restricting to integer values. If I want to implement a QUEST staircase to determine the final threshold ...
Mark L's user avatar
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3 votes
1 answer
59 views

Which unit should be used to compare perceived spatial frequency of 2 different sized image? Cycle per image or cycle per degree?

I am interested in the topic of spatial frequency and its impact on face processing. I have been reading about previous studies that have used different spatial filtering thresholds for their stimuli. ...
gorgorotor's user avatar
2 votes
1 answer
332 views

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). ...
Mik's user avatar
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3 votes
1 answer
196 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 ...
Bastam Tajik's user avatar
0 votes
1 answer
233 views

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/...
CaptainProg's user avatar
3 votes
1 answer
43 views

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 ...
gaspar's user avatar
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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 ...
atsi's user avatar
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6 votes
1 answer
154 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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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 ...
ivan866's user avatar
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2 votes
1 answer
200 views

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 ...
nat's user avatar
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7 votes
6 answers
938 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 ...
AliceD's user avatar
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2 votes
3 answers
141 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 ...
zoozoo's user avatar
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3 votes
2 answers
143 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 ...
Harry Bennett-Snewin's user avatar
2 votes
1 answer
60 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 ...
Postmodern Knight's user avatar
1 vote
1 answer
58 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 ...
umair durrani's user avatar
3 votes
2 answers
146 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 ...
MCon's user avatar
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3 votes
1 answer
52 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 ...
user avatar
3 votes
1 answer
256 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? ...
Muze's user avatar
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3 votes
2 answers
220 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 ...
RECURSIVE FARTS's user avatar
3 votes
1 answer
455 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 ...
user avatar
6 votes
1 answer
915 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 ...
user avatar
3 votes
1 answer
312 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 ...
Lee's user avatar
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2 votes
1 answer
92 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 ...
Cloudy's user avatar
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1 answer
82 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-...
adamk's user avatar
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6 votes
1 answer
903 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/...
Cloudy's user avatar
  • 245
3 votes
1 answer
150 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....
user2957386's user avatar
2 votes
1 answer
214 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 ...
neverMind9's user avatar
-1 votes
2 answers
315 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 ...
Francis's user avatar
1 vote
1 answer
167 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 ...
Amir's user avatar
  • 11
4 votes
2 answers
212 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 ...
Outsider's user avatar
  • 283
3 votes
0 answers
297 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 ...
Maria Maglra's user avatar
3 votes
2 answers
112 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 ...
jjack's user avatar
  • 145
5 votes
2 answers
156 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 ...
irishpippin's user avatar
7 votes
1 answer
867 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 ...
user avatar
3 votes
0 answers
57 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 ...
Girauder's user avatar
  • 113
7 votes
2 answers
214 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: ...
Nathalie's user avatar
  • 343
1 vote
0 answers
51 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 ...
gedanken's user avatar
5 votes
1 answer
329 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. ...
StrongBad's user avatar
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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. ...
Enasi's user avatar
  • 173
4 votes
1 answer
13k 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 ...
danieldaquino's user avatar
4 votes
1 answer
79 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 ...
J. Peter Leeds's user avatar
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.
Nathalie's user avatar
  • 343
3 votes
2 answers
103 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 ...
Remy's user avatar
  • 31
5 votes
1 answer
101 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 ...
Arthur's user avatar
  • 151
4 votes
1 answer
557 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 ...
StrongBad's user avatar
  • 2,633
4 votes
1 answer
612 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 ...
Daphne 33's user avatar
4 votes
1 answer
79 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 ...
Denis Cousineau's user avatar
4 votes
1 answer
2k 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 ...
user135172's user avatar