PEBL Hub — IRB Fact Sheet — 2026-08-23

Hick's Law Task

Category:Processing Speed

Duration:~7 minutes

Parameters:Configurable parameters include number of trials per block (default 50), inter-trial interval range (default 300-500ms), highlight color (default red), key labels, feedback enable/disable, and up to 8 configurable rounds defining which response keys are valid for each block.

Version:1.0

Input:Keyboard

Description

Demonstration of Hick's Law showing that reaction time increases logarithmically with the number of response choices

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.

Device requirements: Desktop or laptop with number row keyboard (1234567890). Numeric keypad not supported. Not compatible with touch/mobile devices.

Scoring & Interpretation

Primary dependent variable is reaction time (RT) as a function of number of response alternatives (numopts). Hick's Law predicts linear relationship between RT and log2(numopts). Typical analysis: plot mean RT vs log2(numopts) and fit linear regression. Slope (b coefficient) reflects information processing rate. Accuracy should remain high (>90%) across all set sizes for valid test. Exclude trials with RT < 150ms (anticipations) or RT > 2000ms (lapses).