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6 votes

Are we able to simulate pain through the brain?

Short Answer It appears that stimulation of the thalamus would invoke feeling of pain: Direct deep brain stimulation (DBS) in the VP thalamus from patients without pain typically evoked nonpainful,...
Chris Rogers's user avatar
  • 12.2k
5 votes

Applying signal detection theory to single-stimulus presentations

There are a huge number of paradigms that SDT can be applied to. The simplest is probably the so-called yes/no paradigm. You present a single stimulus (typically noise alone or signal plus noise) and ...
StrongBad's user avatar
  • 2,633
4 votes
Accepted

Is it possible to calculate d prime if no catch trials were done?

In order to estimate d' for a particular signal level, we need an estimate of the hit rate at that signal level and an estimate of the false alarm (FA) rate. Typically, the FA rate is estimated from ...
StrongBad's user avatar
  • 2,633
4 votes
Accepted

Who first proposed using ROC curves in a psychological context?

I worked out the answer to the question just as I was about to post it. Swets (1973) writes of a 1954 conference that Peterson and Birdsall had presented it a year earlier in a technical ...
user1205901 - Слава Україні's user avatar
3 votes
Accepted

Dependency EEG signals from regions of the brain

The EEG signals between these regions will not be independent. The electrical activity that is being measured at the scalp, is the result of electrical flow inside the brain. This flow does not go in ...
Robin Kramer-ten Have's user avatar
3 votes
Accepted

Doing PCA and ICA analysis on EEG data with 24 channels

First of all, I would recommend working with a domain specific (EEG) and established analysis package of your choice. You mentioned python, so I would advise you to check out MNE-Python. There is a ...
S.A.'s user avatar
  • 310
3 votes

Calculate threshold from 'binary' yes/no data

The biggest drawback of your procedure, also point of discussion previously here is the limited number of trials. Apparently, you obtained binary data, namely one answer (yes/no) per trial, basically ...
AliceD's user avatar
  • 20.7k
2 votes

Understanding a negative correlation between Pc and signal strength

I find that it is the signal strength of the second signal that more so determines correct detection (0,1) The ideal unbiased observer bases the decision on $X1-X2$ while it sounds like your subjects ...
StrongBad's user avatar
  • 2,633
2 votes
Accepted

conservative vs liberal: not related to rate of yes vs no

As I said in this answer, for these types of questions I really like Detection Theory: A User's Guide by Macmillan and Creelman. They consider 3 types of bias ($c$, $c'$, and $\beta$) that differ in ...
StrongBad's user avatar
  • 2,633
2 votes

Independence of criterion and d-prime (psychophysics)

Mathematically, we can see that d' is independent of criterion, regardless of the criterion, by looking at the definition $$d' = Z_D - Z_F.$$ It is tempting to argue that: (1) When the criterion is ...
StrongBad's user avatar
  • 2,633
2 votes
Accepted

Understanding the concept behind d-prime

First lets write down some math for the above figures assuming Gaussian distributions with means $\mu_{n}$ and $\mu_{s}$ both with a standard deviation of unity. In this case the probability of a ...
StrongBad's user avatar
  • 2,633
2 votes
Accepted

Why is threshold at 76% correct when d-prime = 1?

d' is equal to |meanA - meanB|/SD when you have two gaussian distributions of equal variance and different means. Imagine SD=1, meanA = 0, meanB = 1, with B>A as the "correct" answer (...
Bryan Krause's user avatar
  • 7,435
1 vote

Slope of psychometric function too steep?

Regardless of what the chance level exactly was, as alluded to in the comments, the scores leaps from 0.1 to 0.8. This results in nearly vertical slopes that are prone to convergence errors and hence ...
AliceD's user avatar
  • 20.7k
1 vote

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

Any estimate you make is going to be pretty bad. To answer this question requires so many assumptions about the data, experiment, and intended usage, it is just not possible. You would be better off ...
StrongBad's user avatar
  • 2,633
1 vote

how to correctly determine false alarm rate (in a specific experimental setup)

Check out chapter 3 of Macmillan and Creelman on rating scales. You have 3 ratings: left arrow (very confident it is on the left), space bar (not sure), right arrow (very confident it is on the right)....
StrongBad's user avatar
  • 2,633
1 vote

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

For the subject with large response bias, is it still valid to estimate d′ from proportion correct anymore? No. Within the signal detection theory framework, a 2I-2AFC paradigm is identical to a 1I-...
StrongBad's user avatar
  • 2,633
1 vote

Solving for HR and FAR, given ACC and C

I tried to do the math and got stuck. I asked for help at math.se and didn't get any further. My thinking is that it is not possible to write down a nice simple answer even though it is two equations ...
StrongBad's user avatar
  • 2,633
1 vote
Accepted

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

I am unsure as to the exact purpose of your experiment; the title seems to point toward a visual field test, whereas the question body seems to point to a visual acuity (VA) test? Are you interested ...
AliceD's user avatar
  • 20.7k
1 vote
Accepted

Fitting equal-variance signal detection model to ROC data

The cross posting make it hard to answer, but I would rather the points here ... Apart from not running on my machine (something about convert_to_proportions that ...
StrongBad's user avatar
  • 2,633
1 vote

What are some good references for preprocessing and analysis of the P300 response from EEG data in Python?

I don't exactly what it is you are after, but if you are looking for other analyzing techniques, you should try Independent Component Analysis (ICA). I have heard (but I do not have references) that ...
Robin Kramer-ten Have's user avatar
1 vote

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

As you mention Macmillan and Creelman, they talk about 3 types of bias: c, c', and beta. As I said in this answer it normally does not matter which one you use since they are pretty easy to switch ...
StrongBad's user avatar
  • 2,633
1 vote

How to calculate the confidence interval for $d^\prime$ (d prime)?

I haven't done much d-prime stuff for a long time, but perhaps check out the discrim function in the sensR package in R. http://...
Jeromy Anglim's user avatar
1 vote

Upwards of what d' values constitute "good" sensitivity?

There is no standard definition for a "good" value of d'. The index of sensitivity d' can be related to percent correct under certain conditions (unbiased observer, equal probability of signal and no ...
StrongBad's user avatar
  • 2,633

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