Running Glimpse for gap detection

You are going to be using a general-purpose adaptive testing program known as Glimpse, written by Mike Coleman at HCS.


The testing paradigm we will use is a three-interval, three alternative forced-choice (3I-3AFC) task. On each trial you will hear 3 identical noises. In the gap detection task here, two of the noises are continuous, and one has a short gap in it. You choose the noise with the gap in it by selecting the appropriate frog. If you are unsure, guess! There is no point in pondering -- go with your first impulse.


In order to be used with both children & adults, the stimuli are presented with simple animations of three frogs, each of which jumps off its rock in turn. You indicate your response by clicking with the mouse on the frog you think had the tone (or gap) associated with it.


Here's what the test looks like, known as Triples because of the three sounds:

 

This paradigm can be used to test the ability to discriminate more-or-less any contrast. The general rule is to click on the odd one out which may be in any of the three positions.

If you click the correct frog, it jumps into river and you see a tic above its head. Incorrectly clicked frogs jump up a little, and a cross is displayed.


You can also use the keyboard for responding with z, b and m.


Start it be clicking on the appropriate icon. Unusually (and perplexingly), but for a good reason, all you see as the program starts is a blank white screen. RIGHT_CLICK for the main menu.

The tasks so far are

Clicking a task (Use Triples 3AFC) brings up a dialogue box where a name ( used to identify the participant ) is required

Failure to provide a name ends the program.

A directory is created for the named participant in  C:\Documents and Settings\ch_pc\Application Data\Glimpse\Results.
On the lab computers, there is a shortcut to the results in the 'Lab Programs' folder.

 

You are then asked to choose a “specfile” which determines the session.


Choose TriplesGaps.



Quitting Glimpse

Glimpse will inform you when it has finished a particular test. However, if you want to quit early, type 'q' and the program will finish after the next response you make. But you must make a response!

 

The other menu items.

 

The toggle items ( toggle, as in…if already ON, goes OFF…. if already OFF, it goes ON)

 

 

Data ...
takes you to a spreadsheet window where current results are available at the end of a session,

or previous results can be loaded, viewed and charted. Click on the subject results directory on the left to

see a list of files for that subject. Click on a file to have it displayed in the spreadsheet. The contents of the log file which

accompanies all data files is shown in the pane below the directory view. The log file contains the spec file used in the task

and various descriptive statistics computed at the end of the task.

 

Clicking on the file also produces a graph of the adaptive track and some summary statistics.

Threshold  is continuum ( need formula for decibels)

T = test trials

C = catch trials

Z  B  M = left  middle right target display

 

 

 

Data recorded:

 

In essence it is a trial by trial log of all relevant information.

 

SpecPage

loads, modifies and saves specification files

and produces a list of the contents of a directory to help produce stimulus files.

 

 

Specification file
Each session starts with a request for a specification file which you get to choose

from a dialog list, so you can keep them anywhere, but there is a Specs directory ( see below)  in the

Materials subdirectory where example specfiles live. The Lists directory houses the stimulus lists.

 

The Specfile is a plain text file ( made with notepad to avoid including any formatting characters).

The first item is the location and name of the stimulus list and as you can see in this instance it is

written as a program subdirectory. ( “C:\Program Files\Glimpse” is assumed). If you need to keep them

elsewhere then enter the full path.

 

 

The specifcation file simply lists the values of the variables detailed in the table below.

1

Spec_file

ExperimentSpecs

File specifying these variables

 

 

 

 

2

Stimulus_file

includes relative path

Comma-separated columns of continua

3

Design          

Single/Multi

There can be Single or Multiple continua. These will be refered to , SingleToken or MultiToken designs. A Stimulus_file containing more than 1 column of stimuli can run Single or Multiple Token designs.

 

4

Continuum_N           

stimuli in continuum

Assumption is that if MultiToken then the number of tokens in each continuum is the same.

5

Standard_Fixed

True/False

The standard may be fixed or variable within the same continuum, or variable between continua

6

Standard_Start

Integer

First standard

7

Comparison_Start

Integer or “Last”

Last indicates use easiest comparison , first

8

Sample_Replacement

True/False

In MultiToken designs the Standard and Comparison may come from the same of different continua, and may be sampled at random from continua with or without replacement. Standard and Comparison may come from the same or different continua.

 

 

Same_Continuum

True/False

9

Levitt_constant

Integer

Number of consecutive correct trials to make task more difficult

10

Initial_step_size

Integer

15-20% of continuum

11

Final_step_size

Integer

1-2

12

Initial_reversals

Integer

2-4 Number of reversals ignored in final measure.

13

Final_Reversals

Integer

4-8 final reversals that count towards measure

14

Catch_trials

0-1

 0.2  of trials use endpoint (easy)

15

Ignore_trials

Integer

Number of initial trials to ignore

16

Balloons

Boolean

True if rewards required

17

Master_Volume

Long

1-100

18

Wave_Volume

Long

1-100

19

X_pause

Long

Pause before Standard ( leave as is)

20

X_A_pause

Long

Standard to first comparison pause

21

A_B_pause

Long

Pause between left and right comparisons

22

Next_button

True/False

Button to initiate each trial

23

Feedback

True/False

Feedback on accuracy of response

24

Anim

Aliens Castle Frogs

Loads appropriate background

25

Response

Key / Mouse

Sets response mode

26

Max_trials

Integer ( default 50)

Exits at max trials if reversals still not enough

 

 

Watch  is irrelevant for us now, but superimposes relevant information onto the testing screen,  not visible during testing

but is used by the experimenter to verify the program. The Graph plots the standard and continuum

points as the session proceeds, a preview to the unfolding results file can be seen in the spreadsheet,

and the list of variables and their values on the right give a real time view of the progress of the algorithm.

Actual filenames used are also displayed.

 

 

 

Cheat indicates the correct response by a white square above  the correct character.



Making up your Stimulus_file

Use notepad not wordpad or word………just a plain text file.

The first thing the program does is to read your stimulus file list and check that the sound files you refer to

Actually exist. Some simple conventions need to be followed to get your stimulus file to work The list points at sound files and

a stray space for instance can prevent running. If the stimulus file stipulates boing.wav and the file is named

boing .wav (the difference is a space between g and .wav ) an error will be thrown and the program will end.

Case is not important ( boing and BOING ) are equivalent  as are wav and WAV.

 

The first item in a specfile is the stimulus file. This is a list of sound files ordered on  a continuum starting at 0.

 If the first character of each item on the list is “\”, the program will assume that the ensuing directory name is

 a subdirectory of the program subdirectory “Sounds”. Windows systems use the \ (backslash) character to

indicate directories NOT “/”.

 

\Mysounds\wav000.wav

\Mysounds\wav001.wav

\Mysounds\wav002.wav

\Mysounds \wav003.wav

\Mysounds\wav004.wav

\Mysounds\wav005.wav

 

Avoid empty lines at the end of your file. Type last line, hit enter, stop.

 

Otherwise it will expect the full path in the list. (e.g. C:\OtherDirectory\Mysounds\Mycontinuum\wav000.wav).

 

So to keep your lists short, place your continua in the sounds directory and name from there.

 

Program Variables

With watch toggled on, several program variables are on view.

 

 

 

 

continuum_max

Integer

Number of files in the continuum

 continua

Integer

Number of continua

 max_reversals

Integer

Initial + final reversals

 n_reversals

Integer

Current number of reversals

 current_standard

double

 

current_comparison

double

 

 

 

 

 

 

 

 current_trial

Integer

 

 accuracy

Integer

1 / 0

 current_step_size

double

 Modified down be step_increment

current_direction

String

Up/down

 previous_direction

String

Up/down

Step_increment

double

= (Initial_step_size - Final_step_size) / Initial_reversals

Triple_mode

string

2AFC or 3AFC