A method of correcting a person's physical behaviour and improving the person's athletic performance, the method comprising: measuring a characteristic of the person's physical behaviour; determining at a computer device whether said characteristic is outside a predetermined range of values of said characteristic; applying an unconditional stimulus to the person to stimulate an unconditioned response; repeating said steps of measuring, determining and applying to stimulate an adaptation of the physical behaviour. In embodiments, the behaviour may be posture. The measurement may be carried out by one or more gyroscopes and/or accelerometers. The unconditional stimulus may be provided by a vibrator. In an embodiment the method is particularly suitable for use as a horse-riding posture correction device.