CNP VMNM

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Revision as of 18:15, 27 June 2011 by Katie (Talk | contribs) (Task Structure Detail)

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Basic Task Description

This task was designed to be the verbal analogue of the Spatial Maintenance and Manipulation Task CNP_SMNM. Subjects are presented with a set of 4 two letter syllables. In maintenance trials, they remember them as they are while in manipulation trials they must alphabetize them. Then, a single syllable, placed in one of the 4 locations, is displayed and subjects have to indicate if the placement is correct based on trial type.

This version of the task differs from that previously published (Kim et al, 2004, Schizophrenia Research). In the old version, subjects simply had to alphabetize the syllables, and then when presented with a string of 4 letters, indicate whether or not it matched either the target set or the properly alphabetized version. The flaw with this was that in manipulation trials, subjects could guess correctly simply by alphabetizing the syllables presented as a probe, whether or not they remembered the original target or not. This version is more challenging, and more accurately matches the demands of the spatial task.

Task Procedure

Basic Task Info

Trial layout:
1. Target
2. Cue to flip or hold
3. delay
4. Probe
5. ITI

First, subjects undergo an instruction and training period (2 trials each of maintenance and manipulation, and then 4 with trial types intermixed), then the task begins and the subject performs 40 trials (20 trials per condition, randomly selected

Sample Text
"Each trial began with a 1500ms encoding period during which participants were presented with a series of four two letter syllables and were instructed to do their best to remember the exact order of the syllables. Following the encoding phase, a trial-type cue was presented for 1 sec. This cue informed the participant of what cognitive challenge is required for the delay phase. Participants either saw the word “Hold” or “Order”. For trials with the “Hold” or "M" cue, participants were asked to simply remember the locations of the four syllables. During trials with the “Order”, or MnM, cue, participants were asked to mentally alphabetize the syllables. As an additional cue a vertical bar remained across the fixation cross during the delay period, with flat tips if trial was a hold trial and arrow tips if the trial is am order trial. After a 6 sec delay, a set of green lines appearedm marking the locations of the syllables at encoding. In one of the locations was a probe syllable displayed for 1500ms during which participants were to decide whether the location of the probe syllable matched the exact location (in the M condition) or the appropriately alphabetized location (in the MnM condition) of the target syllables."

Task Structure Detail

  • Menu
  • A series of menus appear asking for subject ID, session number, and group number (1 = right handed, 2 = left handed).
  • Training Phase
  • Maintenance Training
  • Instruction slide 1:
"Hold" Trial Instructions
This is a verbal memory test.
You will be shown a set of 4 syllables like this:
Ra Mu Ho Bi
After a few seconds, they will disappear, and a cue saying "HOLD" or "ORDER" will appear, like this:
(showed examples of cues)
  • Instruction slide 2:
If the cue says "HOLD", then remember the syllables in the order you saw them in.

-

If the cue says "ORDER", then put the syllables into alphabetical order and remember them that way.
___ ___ ___ _Bi_
You should press the LEFT key if the syllable was in the location you were supposed to remember it in (either its original position or ::its alphabetized position) and the RIGHT key if it was not.
  • Instruction slide 3:
(examples of correct hold and order trials)
  • Instruction slide 4:
Place your hand on the table with your fingers extended and resting comfortably on the LEFT and RIGHT keys.
Please ask the experimenter to start the PRACTICE when you are ready.


  • Hold/Maintenance Trial Practice- 2 trials
Target- 1500ms
Delay1- 500ms
Delay2- 1000ms - cue to order or hold
Delay3- 6000ms - fixation cross
Probe- 3000ms
Feedback- 1500ms
ITI- 3000ms
  • Manipulation Training
  • Instruction slide 1:
"Order" Trial Instructions
Now you will practice some order trials.
Place your hand on the table with your fingers extended and resting comfortably on the LEFT and RIGHT keys.
Please ask the experimenter to start the PRACTICE when you are ready
  • Order/Manipulation Trial Practice- 2 trials
Target- 1500ms
Delay1- 500ms
Delay2- 1000ms - cue to order or hold
Delay3- 6000ms - fixation cross
Probe- 3000ms
Feedback- 1500ms
ITI- 3000ms
  • Combined Training
  • Instruction slide 1:
Combining Trial Instructions
During the real task, the trial types will be combined, and you will not get feedback on your performance.
Place your hand on the table with your fingers extended and resting comfortably on the LEFT and RIGHT keys.
Please ask the experimenter to start the PRACTICE when you are ready
  • Combined Trial Practice- 6 intermixed trials
Target- 1500ms
Delay1- 500ms
Delay2- 1000ms - cue to order or hold
Delay3- 6000ms - fixation cross
Probe- 3000ms
Feedback- 1500ms
ITI- 3000ms
  • Reminder Instructions:
You are ready to begin the test.
Remember:
In HOLD trials, press the LEFT key if the green syllable is in the same location as it was in the set of yellow syllables, press the RIGHT key if it is not.
In ORDER trials, press the LEFT key if the green syllable is in the location it would be in after the yellow syllables had been put in alphabetical order, press the RIGHT key if it is not.
Place your hand on the table with your fingers extended and resting comfortably on the LEFT and RIGHT keys.


  • Testing Phase- 40 trials, 20 hold and 20 order randomly ordered
Target- 1500ms
Delay1- 500ms
Delay2- 1000ms - cue to order or hold
Delay3- 6000ms - fixation cross
Probe- 3000ms - time limit same as duration, key press advances slide.
Delay- 1500ms (only present in hold condition)
ITI- 3000ms

Task Schematic

Task Parameters Table

Stimuli

Dependent Variables

Cleaning Rules

1. If any of the calculated variables are missing, that subject should be listed for exclusion.
2. If Trial Count is not =40, then that subject should be listed for exclusion.
3. If overall performance (average percent correct) is below 50% (chance, in this task), that subject should be listed for exclusion.
4. If average RT is greater than 6000ms that subject should be listed for exclusion.

It is worth considering dropping people with performance >50% on either maintenance or manipulation (rather than just on the average).

If you want to know if your group looks approximately like it should, in every sample run so far, accuracy is lower in manipulation than maintenance, and reaction time is greater in manipulation than maintenance. This should be the first group level analysis, to quickly verify everything is correct. It would be highly unexpected to have a deviation from this pattern, even though the position along the y axis (overall accuracy or RT) may vary, especially in patient groups.

Code/Algorithms

Calculation rules are all the same as above.

This is the code for data QA, in Stata.
//ALL SUBJECTS
//get breakdown of numbers in each group:
bysort status: summarize ptid
bysort la5ccontrol: summarize ptid
bysort gender: summarize ptid

//see how many complete cases there are.
count if vmnm_main_mn !=.

//exclusions

generate float vmnm_percent_corr=(vmnm_manip_mn + vmnm_main_mn)/2
count if vmnm_percent_corr<=.5
count if vmnm_trialcount != 40 & vmnm_main_tt !=.
count if (vmnm_main_mnrt >6000 | vmnm_manip_mnrt > 6000) & vmnm_main_tt !=.

//create variable summing exclusion criteria
generate float useable_vmnm= 1 if vmnm_trialcount==40 & vmnm_percent_corr>.5 & vmnm_main_mnrt< 6000 & vmnm_manip_mnrt<6000
count if useable_vmnm==1

//SUBJECTS WITH USEABLE DATA
bysort status: summarize ptid if useable_vmnm==1
bysort la5ccontrol: summarize ptid if useable_vmnm==1
bysort gender: summarize ptid if useable_vmnm==1
summarize age vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if useable_vmnm==1
bysort status: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if useable_vmnm==1
bysort la5ccontrol: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if useable_vmnm==1
bysort gender: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if useable_vmnm==1

//COMPLETERS WITH USEABLE DATA
generate float comp_useable_vmnm= 1 if vmnm_trialcount==40 & vmnm_percent_corr>.5 & vmnm_main_mnrt< 6000 & vmnm_manip_mnrt<6000 &status==2
count if comp_useable_vmnm==1
bysort status: summarize ptid if comp_useable_vmnm==1
bysort la5ccontrol: summarize ptid if comp_useable_vmnm==1
bysort gender: summarize ptid if comp_useable_vmnm==1
summarize age vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if comp_useable_vmnm==1
bysort status: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if comp_useable_vmnm==1
bysort la5ccontrol: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if comp_useable_vmnm==1
bysort gender: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if comp_useable_vmnm==1


//OUTLIERS
sktest vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt

grubbs vmnm_manip_mn if comp_useable_vmnm==1, gen (grubb_vmnm_manip_mn)
grubbs vmnm_main_mn if comp_useable_vmnm==1, gen(grubb_vmnm_main_mn)
grubbs vmnm_manip_mnrt if comp_useable_vmnm==1, gen (grubb_vmnm_manip_mnrt)
grubbs vmnm_main_mnrt if comp_useable_vmnm==1, gen(grubb_vmnm_main_mnrt)
grubbs vmnm_percent_corr if comp_useable_vmnm==1, gen(grubb_vmnm_percorr)

generate float comp_useable_nooutlier_vmnm=1 if comp_useable_vmnm==1 & grubb_vmnm_manip_mn !=1 & grubb_vmnm_main_mn !=1 & grubb_vmnm_manip_mnrt !=1 & grubb_vmnm_main_mnrt !=1 & grubb_vmnm_percorr !=1
count if comp_useable_nooutlier_vmnm==1
bysort status: summarize ptid if comp_useable_nooutlier_vmnm==1
bysort la5ccontrol: summarize ptid if comp_useable_nooutlier_vmnm==1
bysort gender: summarize ptid if comp_useable_nooutlier_vmnm==1
summarize age vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if comp_useable_nooutlier_vmnm==1
bysort status: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if comp_useable_nooutlier_vmnm==1
bysort la5ccontrol: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if comp_useable_nooutlier_vmnm==1
bysort gender: summarize vmnm_percent_corr vmnm_main_mn vmnm_manip_mn vmnm_main_mnrt vmnm_manip_mnrt if comp_useable_nooutlier_vmnm==1

histogram vmnm_percent_corr if comp_useable_vmnm==1, frequency bfcolor(gs11) blcolor(black) normal normopts( clcolor(black) ) xtitle(vmnm Overall Percent Correct)
histogram vmnm_main_mn if comp_useable_vmnm==1, frequency bfcolor(gs11) blcolor(black) normal normopts( clcolor(black) ) xtitle(Maintenance Percent Correct (Outliers >50%))
histogram vmnm_manip_mn if comp_useable_vmnm==1, frequency bfcolor(gs11) blcolor(black) normal normopts( clcolor(black) ) xtitle(Manipulation Percent Correct)
histogram vmnm_main_mnrt if comp_useable_vmnm==1, frequency bfcolor(gs11) blcolor(black) normal normopts( clcolor(black) ) xtitle(Maintenance Response Time)
histogram vmnm_manip_mnrt if comp_useable_vmnm==1, frequency bfcolor(gs11) blcolor(black) normal normopts( clcolor(black) ) xtitle(Manipulation Response Time )

Data Distributions

Vmnm all data tables.jpg

Vmnm all useable tables.jpg

Vmnm comp useable tables.jpg

Vmnm com useable nooutlier tables.jpg

Vmnm percorr.jpg

Vmnm maint percorr.jpg

Vmnm manip percorr.jpg

Vmnm maint rt.jpg

Vmnm manip rt.jpg

References