Jenny Phillips
Published 10 March 2026

It has been identified that just fifteen minutes with an animal produces physiological changes within people. Photo by Kh-ali-l i on Pexels.com

Basically, a sense is a biological system that a living organism uses for sensation. This is the process where information is gathered about the environment and world around us through the detection and recognition of stimuli.

What exactly are senses?

During the sensation process the sense organs collect and collate the various stimuli for a process called transduction, which is the process of transforming the information into a form which the brain understands. Both sensation and perception are core fundamental elements to virtually all aspects of human and animal cognition, thought and behaviour. 

Let us break down these sense processes further to develop a greater understanding.

The senses are generally identified by being either internal (interoception) or external (exteroception). The internal senses detect the stimuli from the body’s internal organs and tissue.
External senses detect stimuli from the eyes, skin, ears, mouth, nose, and vestibular system. The senses are a complex system and are not always independent of each other. Touch can further be categorised by deep pressure, light pressure, itch, vibration, hair movement, temperature, and pain while taste can be subdivided into sub modalities of bitter, spicy, salty, sweet, sour and umami. These additional categories are recognised based on their different chemical bindings to the sensory neurons. The brain’s processes then integrate the different senses into one cohesive perceptual experience. This means that information received from one sense can potentially influence how the information from another sense is perceived.

Identifying the sensory organs

These are the organs which sense and give off stimuli. The human body has different sensory organs e.g. nose, mouth, eyes, ear, and skin, all which correspond to a respective bodily system:

• Olfactory system = sense of smell
• Gustatory system = sense of taste
• Auditory system = sense of hearing
• Visual system = sense of vision
• Somatosensory system = sense of touch

What are sensory receptors?

Sensory receptors are cells and structures which detect sensation. Stimuli activate the specialised cells within the peripheral nervous system During the transduction process, the physical stimulus is converted into potential actions by the receptors and these are then transmitted towards the central nervous system for further processing.

How many senses do we have? 5,6,7 or more?

Aristotle (384-322 BC) is identified and credited with first identifying and numbering the senses within his work De Anima. The five common senses have been known for thousands of years and are known to all of us (hearing, sight, sound, touch, and taste). These five however are just the foundation level of our senses. Neurologists generally, agree on the fact that we have at least nine senses.

However, since there is some overlap between senses, different methods of neurological classification can identify some twenty-one senses. This number does not incorporate some physiological experiences like thirst or hunger, though neuroscientists have agreed that our senses include:

• Thermoception – sense of heat (some debate has been had regarding the sense of cold, as some say that this could be a separate sense)
• Equilibrioception – perception of balance
• Nociception – perception of pain
• Proprioception – perception of body awareness

Twenty-one senses sound a lot when we are only familiar with five to seven. But hold that thought…Michael J Cohen, an Eco-psychologist, holds the belief that we in fact have fifty-three senses at our disposal! His definition of a sense goes further than the physiological phenomenon and the nerve sensor definition and his work breaks down the senses into four categories.

1. Radiation senses: sense of colour, sense of moods related to and associated with colour and our sense of temperature.
2. Chemical senses: hormonal sense such as hunger for water, food, or air.
3. Feeling senses: sensitivity to gravity, air pressure, wind and motion.
4. Mental senses: pain both internally and externally, mental, or spiritual distress, sense of self which includes companionship, friendship and power. 

Cohen states that people are all sensory beings and that our human senses form a large part of who we are. He identifies that our senses are provided to us not for indulging ourselves but were mechanisms originally created to aid our survival and to allow us to thrive in the natural world. 

Are all the senses processed by the brain?

All sensory systems send signals to the brain, the brain then interprets the signals and identifies an appropriate response. To enable the brain to do this it often combines information from multiple sensory systems, this process is known as sensory integration.

The human body evolved for the natural world that it lived in and engaged with 24/7. Over time as humans have developed and life has become more industrialised, we have detached ourselves from nature and natural ways of life and, according to the work of Cohen, this has resulted in us using our senses less, which has resulted in them becoming atrophied or sensitised and making us more susceptible to some common ailments. If this is true, then reengaging with nature and the natural world has the potential not only to reconnect us to our origins and roots but also to assist in engaging all our senses and potentially facilitate our resilience to some ailments.

Animals are a good avenue to connect with nature and the natural world and they afford many varied opportunities to stimulate the different human senses and to allow us to receive the benefits from these engagements.

Animals, senses, and their impact on brain chemistry

The release of neurochemicals

Research has identified that when people engage with and interact with animals, through the impact of animals on their senses, they are able to release good neurochemicals. They can double their blood levels of oxytocin and boost their levels of beta endorphins. Beta endorphins increase dopamine levels in the brain, slowing the release of the neurotransmitter gamma aminobutyric acid (which is a natural dopamine inhibitor). Lowering this neurotransmitter allows the brain to release more dopamine, and the combined effect can result in the reduction of pain through the blocking of the pain impulse in the brain.

Dopamine is also identified as working to increase motivation, heighten energy and improve focus. 

Boosting Oxytocin – it has been identified that just fifteen minutes with an animal produces physiological changes within people – the oxytocin levels increase. Oxytocin has been named the “love” or “hug” hormone, and it is a neurotransmitter linked to bonding, love, and affection and is thought to create our sense of comfort and peace. 

Oxytocin production can slow a person’s heart rate and breathing, while reducing a person’s blood pressure and the amount of the stress hormone, cortisol. Oxytocin has also been linked with feelings of trust and safety.  

Because animal interactions have been shown to produce oxytocin, we can safely hypothesise that animal interactions have the ability to reduce feelings of stress and help us to feel calm, under the right circumstances. 

Normalising the brain’s chemistry

It has also been identified that stroking and touching animals can result in an increase of serotonin levels, the neurotransmitter that that many prescribed antidepressants act to increase. Reduced serotonin and dopamine levels are commonly found in different brain-related illnesses like depression, anxiety, and PTSD, and it is also shown to present in those who are experiencing loneliness.

Because animal interactions have been shown to produce serotonin, we can safely hypothesise that animal interactions have the ability to reduce feelings of depression and might help us to feel less lonely or anxious, under the right circumstances. 

How can you use the senses in your work with animal colleagues?