In previous studies we observed a pattern of systematic directional errors when humans pointed to memorized visual target locations in 2-D space. This directional error has also been observed in the initial direction of slow movements towards visual targets or movements to kinesthetically defined targets in 2-D space. In this study we used a perceptual experiment where subjects decide whether an arrow points in the direction of a visual target in 2-D space or not and observed a systematic distortion in direction discrimination known as the "oblique effect". More specifically direction discrimination was better for cardinal directions than oblique. We then used an equivalent measure of direction discrimination in a task where subjects pointed to memorized visual target locations and showed the presence of a motor oblique effect. We finally modeled the oblique effect in the perceptual and motor task using a quadratic function. The model successfully predicted the observed direction discrimination differences in both tasks and furthermore the parameter of the model that was related to the shape of the function was not different between the motor and the perceptual tasks. We conclude that a similarly distorted representation of target direction is present for memorized pointing movements and perceptual direction discrimination.