Introduction

Multitasking can be defined in slightly different ways:

  • Carrying multiple tasks out at the same time

    • Real life: Driving while talking on the phone

    • Laboratory: Drawing a circle with the left hand while drawing a rectangle with the right hand.

  • Carrying out multiple tasks in rapid sequential order

    • Preparing a meal. You cut the vegetables. Put the potatoes in the pan. Sort the spices. Check over the cookbook. Check if potatoes boil. Stir fry the vegetables.

    • Rapidly switching between two computer tasks compared to doing only one task

The reality is that you can argue that people always multi-task in some way. After all, we always monitor our environment to some degree, no matter what. For example, no matter how deeply you concentrate on doing a task, if you hear someone shout "fire", you will process that information and act on it.

In this multitasking experiment, we compare performance when just doing one task compared to when two tasks are mixed. In essence, this is simply a task switching paradigm. It is a cued task switching paradigm, although the cue (the location of the stimulus) and the imperative stimulus are presented at exactly the same time. In that sense, it is a bit mid-way between the alternative run and explicit cued-task paradigm (again, it is a bit a matter of definition).

In this paradigm, we have two different types of comparisons:

  1. Single tasking (doing a block of one task type) compared with multi-tasking (rapidly interleaving two tasks).

  2. Within a multi-tasking block, task-repeat compared with task-switch trials (this is what task-switching paradigms typically study).

Stoet, Connor, O’Connor, and Laws (2013) reported that women are better in switching between two tasks than men (as compared to doing one task at the time).

About this implementation

This example is very close to the task used in the study by Stoet, Connor, O’Connor, and Laws (2013).

Note that this code includes a feedback section and that the code keeps track of which trials are task-repeat and task-switch trials. In principle, this is not necessary unless you want to give participants direct feedback about these things. If you wish, this code can be simpler, but then you would need to calculate these variables in the post-processing for your data analysis. PsyToolkit lets you do it the way you want.

Run the demo

In this experiment, you respond with the keys b and n to diamonds and rectangles (in the shape task) and circles (in the filling task). The instructions are all on screen and require some concentrated reading. Altogether, it will take you 10 to 15 minutes.
If you make a mistake, you get a 3 second timeout. That might feel like a long time, but it is a way to make participants concentrate. You do not need to press a button, just need to wait.
This is a difficult task! You need to remember the rules of two different tasks and you need to frequently switch between them. In the cognitive laboratory, this is considered one of the more difficult tasks. Are you up for it?

Click here to run a demo of the task-switching paradigm

Data output file

In PsyToolkit, the data output file is simply a textfile. The save line of the PsyToolkit experiment script determines what is being saved in the data output file. Typically, for each experimental trial, you would have exactly one line in your text file, and each number/word on that line gives you the information you need for your data analysis, such as the condition, response speed, and whether an error was made.

Meaning of the columns in the output datafile. You need this information for your data analysis.

Colum Meaning

1

blockname

2

tablerow number (1-4)

3

name of task (fill or shape)

4

congruency (congruent or incongruent)

5

response position (left or right )

6

status (1=correct, 2=wrong, 3=slow)

7

response time (milliseconds)

8

mixing (1=in pure block, 2=in mixing block)

9

switching (1=repeat trial, 2=switch trial)

PsyToolkit code

Click to expand the PsyToolkit script code (part of zip file below) 
options
  bitmapdir stimuli
  set &mixingStatus 0 # 1=pure,2=mixed
  set &CurrentTask 0
  set &previousTask 0

fonts
  arial 18
  
bitmaps
  ################# for count down ### ######################
  countdown
  countdown1
  countdown2
  countdown3
  ################# for task switching ######################
  info1
  info2
  info3
  info4
  info5
  info6
  info7
  info8
  info9
  info10
  info11
  fillinginstruction
  shapeinstruction
  shape1fill1  # diamond
  shape1fill2  # diamond
  shape2fill1  # rect 2 filled circles
  shape2fill2  # rect 3 filled circles
  tooslow
  wrongkey
  frame
  gojustshape
  gojustfilling
  gomixshapefilling
  readyreal
  readytraining
  ##
  thankyou

######################################################################
# task switching table
######################################################################

table shapetask
  "shape congruent   left "   shape1fill1  4 1
  "shape incongruent right"   shape2fill1  5 2
  "shape incongruent left "   shape1fill2  4 1
  "shape congruent   right"   shape2fill2  5 2

table fillingtask
  "fill  congruent   left "  shape1fill1  4 1
  "fill  incongruent left "  shape2fill1  4 1
  "fill  incongruent right"  shape1fill2  5 2
  "fill  congruent   right"  shape2fill2  5 2

######################################################################
# task switching tasks
######################################################################

task filling
  table fillingtask
  keys b n
  # -- for later data analysis --------
  set &CurrentTask 1
  if &CurrentTask == &previousTask
    set $taskSwitch 1
  fi
  if &CurrentTask != &previousTask
    set $taskSwitch 2
  fi
  set &previousTask &CurrentTask
  #------------------------------------
  if &CurrentTask == &previousTask
    set $taskSwitch 1
  fi
  if &CurrentTask != &previousTask
    set $taskSwitch 2
  fi
  set &previousTask &CurrentTask
  show bitmap frame              # 1
  delay 800
  show bitmap @2 0 70            # 2
  readkey @4 &maxtime
  clear 2
  if STATUS == WRONG
    show bitmap wrongkey       # 3
    delay 1000
    clear -1
  fi
  if STATUS == TIMEOUT
    show bitmap tooslow         # 3
    delay 1000
    clear -1
  fi
  if STATUS == WRONG || STATUS == TIMEOUT
    show bitmap fillinginstruction # 4
    delay 5000
    clear -1                        # 4
    delay 500
  fi
  save BLOCKNAME TABLEROW @1 STATUS RT &mixingStatus $taskSwitch

task shape
  table shapetask
  keys b n
  # -- for later data analysis --------
  set &CurrentTask 2
  if &CurrentTask == &previousTask
    set $taskSwitch 1
  fi
  if &CurrentTask != &previousTask
    set $taskSwitch 2
  fi
  set &previousTask &CurrentTask
  #------------------------------------
  show bitmap frame                # 1
  delay 800
  show bitmap @2 0 -70             # 2
  readkey @4 &maxtime
  clear 2
  if STATUS == WRONG
    show bitmap wrongkey          # 3
    delay 1000
    clear -1
  fi
  if STATUS == TIMEOUT
    show bitmap tooslow           # 3
    delay 1000
    clear -1
  fi
  if STATUS == WRONG || STATUS == TIMEOUT
    show bitmap shapeinstruction  # 4
    delay 5000
    clear -1
    delay 500
  fi
  save BLOCKNAME TABLEROW @1 STATUS RT &mixingStatus $taskSwitch

# -------------------------------------------------------
#      B L O C K S
# -------------------------------------------------------

######################################################################
#                            B L O C K S
######################################################################

block switchtrainingpureshape      ### TRAINING TASK SWITCHING 1
  pager info1 info2 info3 info4 info5 info6 info7 info8 info9 info10 info11
  message readytraining
  set &maxtime 4000
  set &mixingStatus 1 ## in one-task blocks  
  bitmap gojustshape
  wait_for_key
  bitmap countdown
  delay 1000
  bitmap countdown3
  delay 1000
  bitmap countdown2
  delay 1000
  bitmap countdown1
  delay 1000
  tasklist
    shape   10
  end

message readytraining

block switchtrainingpurefilling
  set &mixingStatus 1 ## in one-task blocks
  bitmap gojustfilling
  wait_for_key
  bitmap countdown
  delay 1000
  bitmap countdown3
  delay 1000
  bitmap countdown2
  delay 1000
  bitmap countdown1
  delay 1000
  tasklist
    filling 10
  end

message readytraining

block switchtrainingmixedshapefilling
  set &mixingStatus 2 ## in interleaved blocks
  bitmap gomixshapefilling
  wait_for_key
  bitmap countdown
  delay 1000
  bitmap countdown3
  delay 1000
  bitmap countdown2
  delay 1000
  bitmap countdown1
  delay 1000
  tasklist
    filling 10
    shape   10
  end

message readyreal

block switchpureshape
  set &mixingStatus 1 ## in one-task blocks  
  bitmap gojustshape
  wait_for_key
  bitmap countdown
  delay 1000
  bitmap countdown3
  delay 1000
  bitmap countdown2
  delay 1000
  bitmap countdown1
  delay 1000
  tasklist
    shape   48
  end

message readyreal

block switchpurefilling
  set &mixingStatus 1 ## in one-task blocks  
  bitmap gojustfilling
  wait_for_key
  bitmap countdown
  delay 1000
  bitmap countdown3
  delay 1000
  bitmap countdown2
  delay 1000
  bitmap countdown1
  delay 1000
  tasklist
    filling 48
  end

message readyreal

block switchmixedshapefilling
  set &mixingStatus 2 ## in interleaved blocks
  bitmap gomixshapefilling
  wait_for_key
  bitmap countdown
  delay 1000
  bitmap countdown3
  delay 1000
  bitmap countdown2
  delay 1000
  bitmap countdown1
  delay 1000
  tasklist
    filling 48
    shape   48
  end
  feedback
    set &PureTrials   mean c7 ; select c6 == 1 && c8 == 1 && c9 == 1
    set &MixedTrials  mean c7 ; select c6 == 1 && c8 == 2 && c9 == 1    
    set &RepeatTrials mean c7 ; select c6 == 1 && c8 == 2 && c9 == 1  
    set &SwitchTrials mean c7 ; select c6 == 1 && c8 == 2 && c9 == 2
    set &MixCost expression &MixedTrials - &PureTrials
    set &SwitchCost expression &SwitchTrials - &RepeatTrials
    text 0 -200 &PureTrials ; prefix "RT in pure trials:" ; postfix "ms"
    text 0 -150 &MixedTrials ; prefix "RT in mixed trials:" ; postfix "ms"
    text 0 -100 &MixCost ; prefix "Mixing cost:" ; postfix "ms"        
    text 0   50 &RepeatTrials ; prefix "RT in task-repeat trials (in mixed blocks):" ; postfix "ms"
    text 0  100 &SwitchTrials ; prefix "RT in task-switching trials (in mixed blocks):" ; postfix "ms"
    text 0  150 &SwitchCost ; prefix "Task-switch cost:" ; postfix "ms"
    text 0  250 "Press space bar."
  end
  
##########################

message thankyou

Download

If you have a PsyToolkit account, you can upload the zipfile directly to your PsyToolkit account. Watch a video on how to do that. If you want to upload the zipfile into your PsyToolkit account, make sure the file is not automatically uncompressed (some browsers, especially Mac Safari, by default uncompress zip files). Read here how to easily deal with this.

Further reading

  • Stoet, G., O’Connor, D.B., Conner, M., and Laws, K. R. (2013). Are women better than men at multitasking? BMC Psychology, 1:18. You can read this open access paper by clicking here.