Sensation and Perception-Chapter 2

Perception

Perception, on the other hand, refers to the processing of this information to make sense of its significance.

Differences : absolute threshold and the threshold of conscious perception

difference between the absolute threshold and the threshold for conscious perception: a stimulus below the absolute threshold will not be transduced, and thus never reaches the central nervous system. A stimulus below the threshold of conscious perception arrives at the central nervous system, but does not reach the higher-order brain regions that control attention and consciousness.

Subliminal perception

subliminal perception often refers to the perception of a stimulus below a given threshold.

Ganglia

Ganglia are collections of neuron cell bodies found outside the central nervous system. Once transduction occurs, the electrochemical energy is sent along neural pathways to various projection areas in the brain, which further analyze the sensory input.

Threshold of conscious perception

It is possible for sensory systems to send signals to the central nervous system, but a person may still not perceive them. This may be because the stimulus is too subtle to demand our attention, or may last for too brief of a duration for the brain to fully process the information.

Nociceptors:

Nociceptors:respond to painful or noxious stimuli (somatosensation)

Sensation

Sensation is performed by receptors in the peripheral nervous system, which forward the stimuli to the central nervous system in the form of action potentials and neurotransmitters.

Transduction

Sensation more appropriately aligns with transduction, which is the conversion of physical, electromagnetic, auditory, and other information from our internal and external environment to electrical signals in the nervous system.

Sensory receptors

Sensory receptors are neurons that respond to stimuli and trigger electrical signals. Sensory receptors may encode multiple aspects of a stimulus.

Weber's Law

Weber's law, which states that there is a constant ratio between the change in stimulus magnitude needed to produce a jnd and the magnitude of the original stimulus. Thus, for higher -magnitude stimuli, the actual difference must be larger to produce a jnd.

Absolute threshold

absolute threshold is the minimum of stimulus energy that is needed to activate a sensory system. It is therefore a threshold in sensation, not in perception.

Difference threshold

difference threshold or just-noticeable difference (jnd) refers to the minimum difference in magnitude between two stimuli before one can perceive this difference.

signal detection theory

signal detection theory, which focuses on the changes in our perception of the same stimuli depending on both internal (psychological) and external (environmental) context.

Threshold

threshold—the minimum amount of a stimulus that renders a difference in perception. There are three main types of thresholds: the absolute threshold, the threshold of conscious perception, and the difference threshold.