Hick's Law Task
System Requirements
Minimum: 1024×768
Recommended: 1280×800
May be challenging for colorblind participants
Description
Demonstration of Hick's Law showing that reaction time increases logarithmically with the number of response choices
About This Test
The PEBL Hick's Law Task demonstrates the fundamental relationship between the number of response alternatives and reaction time, known as Hick-Hyman Law.\n\n**Task Structure**: Participants respond by pressing number keys (1234567890) arranged across the keyboard corresponding to their fingers. On each trial, one of the valid response positions is highlighted in red, and participants must press the corresponding number key as quickly and accurately as possible.\n\n**Block Design**: The task progresses through multiple blocks with increasing response alternatives:\n- Block 1: 1 option (key 5 only)\n- Block 2: 2 options (keys 5-6)\n- Block 3: 3 options (keys 5-6-7)\n- Block 4: 4 options (keys 4-5-6-7)\n- Block 5: 6 options (keys 3-4-5-6-7-8)\n- Block 6: 8 options (keys 2-3-4-5-6-7-8-9)\n\nEach block contains 50 trials by default. Valid response keys are shown in white, while invalid keys appear in dark grey.\n\n**Response Method**: Participants place their hands on the number row with left index finger on 5 and right index finger on 6. This creates a natural finger mapping where each number corresponds to a specific finger position.\n\n**Feedback**: Optional trial-by-trial feedback ('CORRECT' / 'INCORRECT') can be provided based on task parameters.\n\n**Theoretical Basis**: Hick's Law (1952) and Hyman (1953) demonstrated that choice reaction time increases linearly with the logarithm (base 2) of the number of equiprobable alternatives: RT = a + b*log2(n), where n is the number of choices. This relationship reflects the information-processing demands of selecting among multiple response options.\n\n**Use Cases**: Educational demonstration of information processing, human factors research, baseline choice reaction time assessment, and illustration of speed-accuracy tradeoffs in decision making.
Test Details
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Scientific Background
Original Task References:
These references describe the original task that this PEBL implementation is based on.
- Hick, W. E. (1952). On the rate of gain of information. Quarterly Journal of Experimental Psychology, 4(1), 11-26.
- Hyman, R. (1953). Stimulus information as a determinant of reaction time. Journal of Experimental Psychology, 45(3), 188-196.
- Merkel, J. (1885). Die zeitlichen Verhältnisse der Willensthätigkeit. Philosophische Studien, 2, 73-127.
- Teichner, W. H., & Krebs, M. J. (1974). Laws of visual choice reaction time. Psychological Review, 81(1), 75-98.
- Proctor, R. W., & Schneider, D. W. (2018). Hick's law for choice reaction time: A review. Quarterly Journal of Experimental Psychology, 71(6), 1281-1299.
Data Output
hicks-{subnum}.csv
Data Columns
| Column Name | Description |
|---|---|
| subnum | Participant ID |
| block | Block number (1-indexed, increments with each new set size) |
| numtrials | Total number of trials in current block |
| trial | Trial number within current block (1-indexed) |
| opts | Valid response options for this block (pipe-delimited, e.g., '5' or '5|6' or '4|5|6|7') |
| numopts | Number of valid response options (set size: 1, 2, 3, 4, 6, or 8) |
| delay | Inter-trial interval duration in milliseconds (randomly sampled from itiMin to itiMax range) |
| stim | Stimulus position indicated by highlight (1-10 corresponding to keys 1234567890) |
| resp | Participant's key press response (1-10 for keys 1234567890, where 10 represents key 0) |
| correctresp | Correct response value (same as stim, except 10 is recoded to 0 for key '0') |
| correct | Response accuracy (1=correct, 0=incorrect) |
| rt | Reaction time in milliseconds from stimulus onset to key press |
Scoring and Interpretation
About This Test
Demonstration of Hick's Law showing that reaction time increases logarithmically with the number of response choices
Category: Processing Speed
Estimated Duration: 7 minutes
Available Translations: 7 languages
Documentation Sources:
Test implementation, Parameter schema
Documentation Status: Complete