Sensation

What does it mean to sense something? Our sense organs (like our ears and eyes) contain sensory receptors, which are specialized neurons that respond to specific types of information in our physical world. They convert or transduce the external information into neural energy and then send this to the brain. These biological processes collectively are known as sensation. For example, light causes chemical changes in cells that line the back of the eye. These cells relay messages to the central nervous system. Because information from the world around us stimulates our senses, we refer to various types of sensory information as stimuli (singular: stimulus).

You probably know about our five major senses: vision, hearing (audition), smell (olfaction), taste (gustation), and touch (somatosensation). However, we also have sensory systems that provide information about balance (vestibular sense), body position (proprioception), body movement (kinesthesia), pain (nociception), and temperature (thermoception). In this book, we are focusing on hearing and vision.

Perception

Our sensory receptors are constantly collecting information from the environment. However, our interactions with the world are affected by how we interpret that information. Perception refers to the way sensory information is interpreted and consciously experienced. In some cases our brains may receive a message, but we are not consciously aware of it. Over the years there has been a great deal of speculation about the use of subliminal messages in advertising, rock music, and self-help audio programs. Research shows that in laboratory settings, people can process and respond to information outside of awareness. But this does not mean that we obey these messages like zombies; in fact, subliminal messages have little effect on behavior outside the laboratory (Kunst-Wilson & Zajonc, 1980; Rensink, 2004; Nelson, 2008; Radel et al., 2009; Loersch et al., 2013).

Importantly, our perceptions are also shaped by our previous experiences and so influences like culture can affect how we interpret the physical world around us.