Psychology -> Visual perception
This area of study focuses on perception and the general characteristics of the visual sensory system.
• Characteristics of the visual perceptual system.
The process of visual sensation involves the reception, transduction and transmission of light energy.
• Reception is the process of receiving electromagnetic energy from the environment at the site of the visual receptor cells called rods and cones. The visual receptors then transduce the electromagnetic energy into electrochemical energy in the form of neural impulses. The neural energy is then transmitted to the brain via neurons.
Visual perception only begins when light energy has been received and transduced as the result of visual sensation.
• The process of visual perception involves the selection, organisation and interpretation of information. The selection process involves neurons called feature detectors, which respond selectively to specific features of complex stimuli.
• Once the messages reach the brain, the organisation and interpretation processes take place. Organisation is achieved by the grouping of single elements to form a whole. The whole is then interpreted and given meaning. Visual perception is influenced by psychological processes unique to the individual.
The absolute threshold is the smallest magnitude of a stimulus necessary to produce a sensation that can be detected 50% of the time. For example, under ideal conditions, the absolute threshold for hearing is the tick of a watch 20 feet away.
The absolute threshold for hearing - distance 20 feet
The just noticeable difference (JND) is the smallest difference between two particular stimuli.