Assignment: Creating an Adaptation Experiment

In this assignment, your task is to write an OpenSesame program to run an adaptation experiment. The purpose of the experiment is to demonstrate the existence of orientation-selective mechanisms in human vision, using a systems-analytic psychophysical approach. The experiment is also illustrative of many different types of experiments in psychology, cognitive science, and other sciences, involving the use of controls, and the presentation and interpretation of data.

Background videos on orientation-selective cells:

https://youtu.be/v20-E_2bT2c https://youtu.be/N2Zaxm86IIo

The experiment will demonstrate that using very simple equipment, provided some care is exercised, input/output measurements can be obtained that allow considerable insight into the functional operations of the human brain – in this instance the visual pathway.

Briefly, in the experimental condition, observers will adapt (by continuous staring) for 90 seconds to a grating (black and white bars) that is oriented at an angle of 12 degrees rotated anti-clockwise, or left of vertical (anti-clockwise is defined as negative, thus –12 deg). After adaptation observers will be required to measure the angle of grating that now looks vertical. If staring at an oriented grating affects later perception of orientation of other gratings, we are led to the conclusion that mechanisms in the visual system that are selective for orientation have been affected. The post-adaptation effect is known as the “tilt after-effect”. The psychophysical method to be used is called “method of constant stimuli”.