Stoppage Criteria: max incorrect

bcipy/helpers/task.py

@@ -444,3 +444,22 @@ def generate_targets(alp, stim_number):
     targets = [target for sublist in lists for target in sublist]
 
     return targets
+
+
+def consecutive_incorrect(target_text: str, spelled_text: str) -> int:
+    """Function that computes the number of consecutive symbols that
+    are incorrectly spelled.
+
+    >>> consecutive_incorrect('WORLD', 'H')
+    1
+    >>> consecutive_incorrect('WORLD', 'W')
+    0
+    >>> consecutive_incorrect('WORLD', 'WOHL')
+    2
+    """
+    if not target_text:
+        return len(spelled_text)
+    for i, character in enumerate(spelled_text):
+        if character != target_text[i]:
+            return len(spelled_text[i:])
+    return 0

bcipy/helpers/tests/test_task.py

@@ -1,20 +1,18 @@
 import unittest
-
-from typing import List
 from collections import Counter
-from mockito import unstub, mock, when, verify, verifyStubbedInvocationsAreUsed
+from typing import List
 
 import numpy as np
 import psychopy
+from mockito import mock, unstub, verify, verifyStubbedInvocationsAreUsed, when
 
 from bcipy.acquisition import LslAcquisitionClient
 from bcipy.acquisition.record import Record
-from bcipy.task.exceptions import InsufficientDataException
-
-from bcipy.helpers.task import (_float_val,
-                                calculate_stimulation_freq, construct_triggers,
+from bcipy.helpers.task import (_float_val, calculate_stimulation_freq,
+                                consecutive_incorrect, construct_triggers,
                                 generate_targets, get_data_for_decision,
                                 get_key_press, target_info)
+from bcipy.task.exceptions import InsufficientDataException
 
 
 class TestCalculateStimulationFreq(unittest.TestCase):
@@ -319,5 +317,19 @@ def test_get_data_for_decision_throws_insufficient_data_error_if_data_query_out_
             get_data_for_decision(inquiry_timing, self.daq)
 
 
+class TestUtils(unittest.TestCase):
+    """Tests for utility functions"""
+
+    def test_consecutive_incorrect(self):
+        """Test calculation of consecutive incorrect"""
+        self.assertEqual(
+            0, consecutive_incorrect(target_text='', spelled_text=''))
+        self.assertEqual(0, consecutive_incorrect('WORLD', ''))
+        self.assertEqual(0, consecutive_incorrect('WORLD', 'W'))
+        self.assertEqual(0, consecutive_incorrect('WORLD', 'WORLD'))
+        self.assertEqual(1, consecutive_incorrect('WORLD', 'H'))
+        self.assertEqual(2, consecutive_incorrect('WORLD', 'WOHL'))
+
+
 if __name__ == '__main__':
     unittest.main()

bcipy/parameters/parameters.json

@@ -611,6 +611,14 @@
     "recommended_values": "",
     "type": "int"
   },
+  "max_incorrect": {
+    "value": "5",
+    "section": "bci_config",
+    "readableName": "Maximum Number of Incorrect Selections",
+    "helpTip": "The maximum number of consecutive incorrect selections for copy/spelling tasks. The task will end if this number is reached.",
+    "recommended_values": "",
+    "type": "int"
+  },
   "decision_threshold": {
     "value": "0.8",
     "section": "bci_config",

bcipy/task/paradigm/rsvp/copy_phrase.py

@@ -22,7 +22,8 @@
 from bcipy.helpers.session import session_excel
 from bcipy.helpers.stimuli import InquirySchedule, StimuliOrder
 from bcipy.helpers.symbols import BACKSPACE_CHAR, alphabet
-from bcipy.helpers.task import (construct_triggers, fake_copy_phrase_decision,
+from bcipy.helpers.task import (consecutive_incorrect, construct_triggers,
+                                fake_copy_phrase_decision,
                                 get_device_data_for_decision, get_user_input,
                                 relative_triggers, target_info,
                                 trial_complete_message)
@@ -94,7 +95,8 @@ class RSVPCopyPhraseTask(Task):
         'font', 'fixation_color', 'trigger_type',
         'filter_high', 'filter_low', 'filter_order', 'notch_filter_frequency', 'down_sampling_rate', 'prestim_length',
         'is_txt_stim', 'lm_backspace_prob', 'backspace_always_shown',
-        'decision_threshold', 'max_inq_len', 'max_inq_per_series', 'max_minutes', 'max_selections', 'min_inq_len',
+        'decision_threshold', 'max_inq_len', 'max_inq_per_series', 'max_minutes', 'max_selections', 'max_incorrect',
+        'min_inq_len',
         'show_feedback', 'feedback_duration',
         'show_preview_inquiry', 'preview_inquiry_isi', 'preview_inquiry_error_prob',
         'preview_inquiry_key_input', 'preview_inquiry_length', 'preview_inquiry_progress_method',
@@ -416,6 +418,15 @@ def check_stop_criteria(self) -> bool:
                              '(configured with the max_selections parameter)')
             return False
 
+        if consecutive_incorrect(
+                target_text=self.copy_phrase,
+                spelled_text=self.spelled_text) >= self.parameters.get(
+                    'max_incorrect', 3):
+            self.logger.info(
+                'Max number of consecutive incorrect selections reached '
+                '(configured with the max_incorrect parameter)')
+            return False
+
         return True
 
     def next_target(self) -> str:

bcipy/task/tests/paradigm/rsvp/test_copy_phrase.py

@@ -50,6 +50,7 @@ def setUp(self):
             'max_minutes': 20,
             'min_inq_len': 1,
             'max_selections': 50,
+            'max_incorrect': 10,
             'notch_filter_frequency': 60.0,
             'preview_inquiry_isi': 1.0,
             'preview_inquiry_key_input': 'space',