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BrainStreamExampleSpellerPart1 (view source)
Revision as of 16:05, 26 September 2018
, 16:05, 26 September 2018→Evaluation of the speller
Below, a flowchart of the Train block is shown:
Below, a flowchart of the Train block is shown:
[[File:DocsSectionsExampleSpellerPart1_flowchart.png|656px|261x]]
[[File:DocsSectionsExampleSpellerPart1_Flowchart.png|656px|261x]]
''Figure 1: Flowchart''
''Figure 1: Flowchart''
A [[BrainStreamPlugIns|imported] table (StimDisplay in speller_common) is used to define all actions related to stimulus presentation. You can see the reference to this imported table in the 9th row of the main Actions table: '@speller_common.edt StimDisplay'. The imported table is shown below:
A [[BrainStreamPlugIns|imported] table (StimDisplay in speller_common) is used to define all actions related to stimulus presentation. You can see the reference to this imported table in the 9th row of the main Actions table: '@speller_common.edt StimDisplay'. The imported table is shown below:
[[File:DocsSectionsExampleSpellerPart1_speller_common_actions_2.png|832px|167x]]
[[File:DocsSectionsExampleSpellerPart1_Speller_common_actions_2.png|832px|167x]]
''Figure 2: StimDisplay imported table.''
''Figure 2: StimDisplay imported table.''
| stimSequence || several repetitions of highlighting all rows (1-3) and columns (4-6) || 231546 132654 312645 ...
| stimSequence || several repetitions of highlighting all rows (1-3) and columns (4-6) || 231546 132654 312645 ...
|-
|-
| stimDict || <p>dictionary: translates stimulus numbers to grids with ones for <br />highlighted elements and zeros for non highlighted elements</p> || [[File:DocsSectionsExampleSpellerPart1_stimDict.png|225px|61x]]
| stimDict || <p>dictionary: translates stimulus numbers to grids with ones for <br />highlighted elements and zeros for non highlighted elements</p> || [[File:DocsSectionsExampleSpellerPart1_StimDict.png|225px|61x]]
|-
|-
| stimCode || current stimulus number || 3
| stimCode || current stimulus number || 3
|-
|-
| curStim || <p>current stimulus grid (ones for highlighted elements and <br />zeros for non highlighted elements)</p> || [[File:DocsSectionsExampleSpellerPart1_curStim.png|78px|66x]]
| curStim || <p>current stimulus grid (ones for highlighted elements and <br />zeros for non highlighted elements)</p> || [[File:DocsSectionsExampleSpellerPart1_CurStim.png|78px|66x]]
|}
|}
When the sequence is initialized, the epoch counter is increased by 1 and the speller grid is shown. Immediately afterwards, the highlightGrid function is executed. This function determines the number of the current stimulus (stimCode) and the corresponding grid (curStim), displays the correct image on the screen and inserts the marker highlightOn. After 0.05 seconds, the non-highlighted grid is shown. Another 0.05 seconds later, a decision is made whether to show another stimulus or end the sequence.
When the sequence is initialized, the epoch counter is increased by 1 and the speller grid is shown. Immediately afterwards, the highlightGrid function is executed. This function determines the number of the current stimulus (stimCode) and the corresponding grid (curStim), displays the correct image on the screen and inserts the marker highlightOn. After 0.05 seconds, the non-highlighted grid is shown. Another 0.05 seconds later, a decision is made whether to show another stimulus or end the sequence.
== Data selection ==
== Data selection ==
As explained in the introduction, the visual speller is based on the brain response to the flashing rows and columns. Therefore, we need to collect a certain amount of data after each flash. The highlightGrid function (see the [[#StimPres|Stimulus presentation section]]), inserts a marker highlightOn each time a row or column of the grid is highlighted. As we need accurate synchronization with the data, this marker is inserted [[BrainStreamMarkerHandling#HardwareMarker|via the hardware]]. Data selection is specified for the highlightOn marker in the speller_common import-table. This is the import-tables' [[BrainStreamBuildingExperiments#SecDataSel|DataSelection table]:
As explained in the introduction, the visual speller is based on the brain response to the flashing rows and columns. Therefore, we need to collect a certain amount of data after each flash. The highlightGrid function (see the [[#StimPres|Stimulus presentation section]]), inserts a marker highlightOn each time a row or column of the grid is highlighted. As we need accurate synchronization with the data, this marker is inserted [[BrainStreamMarkerHandling#HardwareMarker|via the hardware]]. Data selection is specified for the highlightOn marker in the speller_common import-table. This is the import-tables' [[BrainStreamBuildingExperiments#SecDataSel|DataSelection table]]:
[[File:DocsSectionsExampleSpellerPart1_speller_common_data.png|456px|53x]]
[[File:DocsSectionsExampleSpellerPart1_Speller_common_data.png|456px|53x]]
''Figure 4: DataSelection table''
''Figure 4: DataSelection table''
Each time a row or column of the grid was highlighted, the highlightOn marker was inserted. Thus, in the log file we can look up what the time between two successive highlightOn markers was. These are the first three highlightOn markers:
Each time a row or column of the grid was highlighted, the highlightOn marker was inserted. Thus, in the log file we can look up what the time between two successive highlightOn markers was. These are the first three highlightOn markers:
<pre>18Nov11|14:39:43.559 INFO > '''***''' ( highlightOn) '''*************************************************************'''
<pre>18Nov11|14:39:43.559 INFO > ***** ( highlightOn) *************************************************************
18Nov11|14:39:43.559 INFO > 17.10 (eeg:#2972.00) 17.10 17.29 act: getvar (t=EVENT) highlightOn
18Nov11|14:39:43.559 INFO > 17.10 (eeg:#2972.00) 17.10 17.29 act: getvar (t=EVENT) highlightOn
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18Nov11|14:39:43.682 INFO > '''***''' ( highlightOn) '''*************************************************************'''
18Nov11|14:39:43.682 INFO > ***** ( highlightOn) *************************************************************
18Nov11|14:39:43.683 INFO > 17.23 (eeg:#3007.00) 17.23 17.42 act: getvar (t=EVENT) highlightOn
18Nov11|14:39:43.683 INFO > 17.23 (eeg:#3007.00) 17.23 17.42 act: getvar (t=EVENT) highlightOn
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18Nov11|14:39:43.897 INFO > '''***''' ( highlightOn) '''*************************************************************'''
18Nov11|14:39:43.897 INFO > ***** ( highlightOn) *************************************************************
18Nov11|14:39:43.897 INFO > 17.36 (eeg:#3039.00) 17.36 17.63 act: getvar (t=EVENT) highlightOn
18Nov11|14:39:43.897 INFO > 17.36 (eeg:#3039.00) 17.36 17.63 act: getvar (t=EVENT) highlightOn
</pre>
</pre>
These are the last three highlightOn markers:
These are the last three highlightOn markers:
<pre>18Nov11|14:40:25.825 INFO > '''***''' ( highlightOn) '''*************************************************************'''
<pre>18Nov11|14:40:25.825 INFO > ***** ( highlightOn) *************************************************************
18Nov11|14:40:25.825 INFO > 58.80 (eeg:#13647.00) 58.80 59.56 act: getvar (t=EVENT) highlightOn
18Nov11|14:40:25.825 INFO > 58.80 (eeg:#13647.00) 58.80 59.56 act: getvar (t=EVENT) highlightOn
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18Nov11|14:40:25.835 INFO > '''***''' ( highlightOn) '''*************************************************************'''
18Nov11|14:40:25.835 INFO > ***** ( highlightOn) *************************************************************
18Nov11|14:40:25.835 INFO > 58.96 (eeg:#13688.00) 58.96 59.57 act: getvar (t=EVENT) highlightOn
18Nov11|14:40:25.835 INFO > 58.96 (eeg:#13688.00) 58.96 59.57 act: getvar (t=EVENT) highlightOn
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18Nov11|14:40:25.844 INFO > '''***''' ( highlightOn) '''*************************************************************'''
18Nov11|14:40:25.844 INFO > ***** ( highlightOn) *************************************************************
18Nov11|14:40:25.845 INFO > 59.12 (eeg:#13730.00) 59.12 59.58 act: getvar (t=EVENT) highlightOn </pre>
18Nov11|14:40:25.845 INFO > 59.12 (eeg:#13730.00) 59.12 59.58 act: getvar (t=EVENT) highlightOn </pre>