mit-app-inventor

APCSPStroopExample

About this app

The APCSPStroopExample app is described in the Screen1.AboutScreen.

This app ​demonstrates ‘…the delay in reaction time between congruent and incongruent stimuli​’ known as the Stroop Effect — try​ to say the color of the word, not the word itself.​

The app illustrates all aspects of the APCS-P requirements for the Create Performance Task:
• List storing and access used to manage the complexity of the program;
• A procedure w/ a parameter that is called from different places with different values and whose behavior varies based on the value of the parameter; and
• An algorithm that includes sequencing, selection, and repetition.

Code (PC)

• The Reset Button invokes the reset procedure, which invokes the stroop procedure to shuffle the color names and their colors.
• Button1, Button2, Button3, Button4, Button5, Button6, and Button7 do nothing, but provide the canvas for the names and their colors.
• The Matching Button invokes the stroop procedure with a flag specifying that the word colors match the word names.
• The Shuffled Button invokes the stroop procedure with a flag specifying that the word colors do not match the word names.

Written response (WR)

The submission for the APCS-P Create Performance Task includes a written response to questions 3a (i-iii), 3b (i-v), 3c (i-iv), and 3d (i-iii) to meet the requirements of the scoring guidelines.

Row 1

• The purpose of the program is to demonstrate the Stroop Effect, ‘…the delay in reaction time between congruent and incongruent stimuli’ used as part of a concussion protocol to help evaluate potential concussions. The classic experiment demonstrated by John Ridley Stroop in 1935 asks subjects to say the color of the text under two conditions: where the color matches the text and where the color does not match the text. The ability of subjects to correctly name the colors — and the speed with which they perform — is an indication of neurological function.
• The function of the program is to present subjects with a shuffled list of color names with matching colors or a shuffled list of color names with shuffled colors so they can administer the Stroop test.
• The input of the program is clicking either of the two Buttons — Matching or Shuffle. The output of the program is presenting subjects with a shuffled list of color names with matching colors (when the Matching Button is clicked) or a shuffled list of color names with shuffled colors (when the Shuffled Button is clicked).

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Row 2

• The nameIndexes list is a local variable both stored and used in the program code for the stroop procedure (above) to partially fulfill the programs purpose.
• In the program code for the stroop procedure (above), the nameIndexes list is stored as a local variable by the shuffle procedure, shuffling a range of integers.

• In the program code for the stroop procedure (above), the nameIndexes list is used, in turn, by the stroop procedure to initialize another local variable (colorIndexes), shuffling a copy of the nameIndexes list if the shuffle? parameter is true.

  For example (if the shuffle? parameter is true), because shuffling is random, the stroop procedure might generate the following 7-element lists:

List	Index 1	Index 2	Index 3	Index 4	Index 5	Index 6	Index 7
rangeList	1	2	3	4	5	6	7
nameIndexes	7	1	6	3	4	5	2
colorIndexes	6	7	2	4	5	3	1

• So as to not present the same Stroop test to the user every time, the nameIndexes list represents the shuffled names of colors and the colorIndexes list (which is the shuffled nameIndexes list when the shuffle? parameter is true) represents the colors of the names. In the example, the Button at index 1 will have the color name at index 7 and the color at index 6, the Button at index 2 will have the color name at index 1 and the color at index 7, etc. This assumes that the global names list and the global colors list (shown in the program code above) are parallel lists with corresponding elements.

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Row 3

• In the program code for the shuffle procedure (above), the heart of Satollo’s Algorithm is in swapping the elements of the list(s). Using list(s) to contain the shuffled elements manages the complexity of the program code, because the alternative to the program code for the swap procedure (above) which swaps the elements of the list(s), is to use a fixed number of (global) variables to achieve the same result. For example, even with only three elements (global variables element1, element2, element3), the code for an example swapVariables procedure could be:

• This approach is clearly more complex even with only three elements, while a typical Stroop Test involves seven or more elements. Such a procedure is quadratically complex — 𝑂(n²) — and would require code changes for every added element, whereas adding to the global names and the global colors parallel lists with new corresponding elements would not require any program code changes.

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Row 4

• The stroop procedure (above) is a student-developed procedure with at least one parameter that has an effect on the functionality of the procedure. The parameter shuffle? is a Boolean value that determines whether the colorIndexes local-variable list is a shuffled copy of the nameIndexes local-variable list or whether the colorIndexes local-variable list is a reference to the nameIndexes parameter and not shuffled relative to it.

• The ButtonMatching.Click event (above) shows where the student-developed procedure (stroop) is called with a false value for the shuffle? parameter — which is tested prior to shuffling the colorIndexes local-variable list resulting in the shuffled color names matching the colors. The ButtonShuffled.Click event (above) shows where the student-developed procedure (stroop) is called with a true value for the shuffle? parameter — which is tested prior to shuffling the colorIndexes local-variable list resulting in the shuffled color names not matching the colors.

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Row 5

• The stroop procedure (above) is a student-developed algorithm that includes sequencing (more than one program block), selection (an if / else block that either shuffles or does not shuffle the nameIndexes local-variable list), and iteration (a for each counted loop that sets the properties of Buttons in the buttons global-variable list).
• To set up a Stroop Test, the student-developed algorithm works as follows:
  • Given three global-variable, fixed, parallel lists with corresponding elements. The lists are: buttons (containing references to the buttons whose text and text colors are to be modified), names (containing color names), and colors (containing colors corresponding to the color names).
  • Create two lists corresponding to the indexes of the names and colors lists. Shuffle the nameIndexes list (the indexes of the names list) relative to the indexes in order. Either shuffle the colorIndexes list (the indexes of the colors list) relative to the nameIndexes list (in the shuffled Stroop Test) or do not shuffle the colorIndexes list (the indexes of the colors list) relative to the nameIndexes list (in the matching Stroop Test).
  • Iterate through the buttons list, setting the text for each button to the name referred to in the names list indexed indirectly by the index in the corresponding position in the nameIndexes list and setting the color for each button to the color referred to in the colors list indexed indirectly by the index in the corresponding position in the colorIndexes list.
  • The shuffle procedure is a version of Satollo’s Algorithm that shuffles lists in place.

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Row 6

• The ButtonMatching.Click event (above) shows where the student-developed procedure (stroop) is called with a false value for the shuffle? parameter — which is tested prior to shuffling the colorIndexes local-variable list resulting in the shuffled color names matching the colors.
• The ButtonShuffled.Click event (above) shows where the student-developed procedure (stroop) is called with a true value for the shuffle? parameter — which is tested prior to shuffling the colorIndexes local-variable list resulting in the shuffled color names not matching the colors.

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Video (V)

The submission for the APCS-P Create Performance Task includes a video that, ‘…demonstrates the running of [the] program.’

Color notes

• The purple color is Rebecca Purple, which is a tribute to Eric Meyer’s daughter Rebecca.
• The orange color is Swamp Holly Orange, which is the the color of the logotype of Yellow Transit (and is also paint color 60039).

Designer

All components retain their default properties, — except Width and Height set to Fill parent... where necessary to center UX components, Button text(s) changed from their defaults(s), and Screen1.AboutScreen set to the explanatory text (above).

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