PEBL Span Variants Test
Version 0.1

OVERVIEW
This test combines multiple working memory span variants commonly used by
cognitive testing enthusiasts to assess their cognitive abilities. It allows
running multiple span tasks in a single session with configurable ordering.

TASK VARIANTS
The test includes nine different span task variants:

1. Forward Digit Span
   - See digits one at a time, recall in same order
   - Classic working memory measure

2. Backward Digit Span
   - See digits one at a time, recall in reverse order
   - Tests working memory manipulation

3. Forward Letter Span
   - See letters one at a time, recall in same order
   - Uses easily distinguishable letter set (ABCDFHKLMR by default)

4. Backward Letter Span
   - See letters one at a time, recall in reverse order
   - Working memory manipulation with verbal stimuli

5. Forward Mixed Span
   - See digits and letters one at a time, recall in same order
   - Tests working memory for mixed alphanumeric sequences

6. Backward Mixed Span
   - See digits and letters one at a time, recall in reverse order
   - Tests manipulation of mixed alphanumeric information

7. Digit Ordering
   - See multiple digits simultaneously
   - Recall them in numerical order (smallest to largest)
   - Tests ability to manipulate and sequence information

8. Letter Ordering
   - See multiple letters simultaneously
   - Recall them in alphabetical order
   - Tests sequencing of verbal information

9. Mixed Ordering
   - See mix of digits and letters simultaneously
   - Recall with digits first (numerical order), then letters (alphabetical)
   - Tests dual sequencing and categorization

CONFIGURATION
Each variant can be enabled/disabled independently via parameters.
Set the variant's order parameter to:
  - 0 to skip that variant
  - Any other number to specify execution order (1, 2, 3, etc.)

The test will run enabled variants in ascending order based on their
order parameter values.

BASED ON
This test extends the PEBL Digit Span task with additional variants
and flexible configuration for cognitive self-assessment.

REFERENCES
Forward/backward digit span are traditional neuropsychological measures.
Letter span and ordering tasks are commonly used in working memory research
and cognitive training assessment.
