Stimulus Salience refers to how obvious or prominent a stimulus is in a person’s environment. If a person has visual deficits, then visual stimulus will not have as much salience as auditory stimulus, for example. In order to notice stimulus, and for that stimulus to have salience, a learner must possess pre-attending skills necessary for the setting. The pre-attending skills for kindergarten, for example, include looking at the instructional materials, listening to instructions and to the teacher and sitting quietly while instruction is happening.
Masking is when the salience of a stimulus is decreased. A competing stimulus blocks the evocative power of the stimulus, decreasing its effectiveness. For example, a teenager may follow directions when alone with a parent, have a more difficult time when peers are present. This example is competition of different contingencies of reinforcement which makes it more difficult for the subject to mind the discriminant stimulus.
Overshadowing is when the first stimulus has no more stimulus control. An example is a teenager who can study in a classroom, but not in front of the a group of cheerleaders.
In order to reduce the effect of overshadowing and masking, we must apply antecedent interventions such as: arranging the environment to reduce “noise” from unwanted stimulus, making the instructional stimuli intense and consistently reinforcing behavior in the presence of desired stimulus.