Fixed Ratio
Overview
The fixed ratio (FR) schedule is one of the four foundational reinforcement schedules described by B.F. Skinner. Under an FR schedule, a reinforcer is delivered after a fixed, predictable number of responses — for example, FR5 requires exactly five lever presses per pellet. FR schedules produce a characteristic "break-and-run" response pattern: a post-reinforcement pause followed by a rapid burst of responding until the next reinforcer is earned.
FR schedules are widely used in operant training, dose-response studies, and as baseline schedules before transitioning to more complex paradigms such as progressive ratio. The ratio requirement can range from FR1 (continuous reinforcement, used for initial shaping) to FR50 or higher, with higher ratios producing longer post-reinforcement pauses and lower overall response rates.
ConductMaze automates FR scheduling with precise response counting, reinforcer delivery, and real-time data logging. The software supports rapid switching between ratio values for within-session dose-response designs and provides automated cumulative-record generation for visual analysis of response patterns.
Trial Flow
Session Start
House light ON, levers extended, session timer begins
Active Lever Press
Subject presses the active lever
Response Counter
Has response count reached ratio requirement?
Reinforcer Delivery
Pellet dispensed, cue light activated
Counter Reset
Response counter resets to zero for next ratio
Session Limit Check
Max reinforcers or time limit reached?
Session End
Levers retracted, data saved
Parameters
| Parameter | Type | Default | Description |
|---|---|---|---|
| Ratio Value | integer | 5 | Number of responses required per reinforcer (e.g., FR1, FR5, FR10) |
| Max Reinforcers | integer | 50 | Maximum number of reinforcers before session ends |
| Max Session Time | seconds | 3600 | Absolute session time limit |
| Active Lever Side | enum | Right | Which lever is reinforced (Left, Right, Counterbalanced) |
| Cue Light Duration | seconds | 3 | Duration of cue light paired with reinforcer delivery |
| Timeout Period | seconds | 0 | Post-reinforcement timeout during which responses are recorded but not reinforced |
| Reinforcer Type | enum | Sucrose Pellet | Type of reinforcement delivered (sucrose pellet, food pellet, liquid) |
Metrics
| Metric | Unit | Description |
|---|---|---|
| Total Active Presses | count | Total presses on the active lever |
| Total Inactive Presses | count | Total presses on the inactive lever (discriminability control) |
| Reinforcers Earned | count | Total reinforcers delivered during the session |
| Response Rate | presses/min | Mean rate of active lever pressing across the session |
| Post-Reinforcement Pause | seconds | Mean time between reinforcer delivery and next active press |
| Latency to First Press | seconds | Time from session start to first active lever press |
| Inter-Response Time | seconds | Mean time between successive active lever presses |
Sample Data
| Trial | Active_Presses | Inactive_Presses | PRP_s | Rate_ppm | Latency_s |
|---|
Representative data for illustration purposes. Actual values will vary by species, strain, and experimental conditions.
Applications
- 1Initial operant training — FR1 continuous reinforcement for lever-press shaping and acquisition
- 2Dose-response assessment — comparing response rates across drug doses on a stable FR baseline
- 3Feeding behavior — measuring consummatory motivation with food or sucrose reinforcers
- 4Baseline schedule — establishing stable responding before transitioning to PR or extinction
- 5Motor function screening — detecting drug-induced changes in response capacity
Related Protocols
Compatible Products
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