When a video of a chimp called Mahale reuniting with her newborn baby Kucheza went viral, the world fell in love. Perhaps these videos ignite so much emotion because they show us we're not alone in our consciousness. After watching this interaction, how could we deny that animals have thoughts, feelings, and consciousness?
In recent years, scientists have determined that many nonhuman species do have consciousness; the more significant challenge now is to define that consciousness and learn how different creatures experience their internal and external worlds.
What Is Consciousness?
Consciousness is defined as "the state of being aware and responsive to one's surroundings." Human consciousness allows us to process internal and external stimuli and develop responses. It means we are aware of our unique thoughts, interpretations, emotions, and experiences. The big question is, are we alone in our consciousness?
Today, science can answer this question with a definitive no. We are not the only conscious beings on the planet, many other animals demonstrate consciousness. A better question is, how can we measure the consciousness of different animals?
How Can We Measure Consciousness?
Measuring the consciousness of nonhuman species is challenging because they cannot use language to communicate their experiences with us. Still, if we base consciousness firmly on verbal communication abilities, we would say that babies, toddlers, and anyone who has lost the ability to communicate is also not conscious. We know that this isn't true.
There is no single or definitive way to measure consciousness; still, a 2020 paper published by Jonathan Birch and his colleagues puts forward an intriguing framework. Below is a summary of these parameters, which can help us to define an animal's level of consciousness.
The first dimension by which we can measure the consciousness of an animal is via perceptual richness, which refers to the clarity of senses that help an animal understand the world around them. Perceptive abilities are broken down into different modalities, such as vision or olfactory. Scientists score animals on these individual elements of perception rather than awarding an overall grade.
The reason for this is that the strength of each modality varies wildly, so applying a universal score wouldn't provide an accurate indication of sensory ability. For example, sharks do not have a well-developed sense of taste because it serves no purpose in helping them to find food. But they have an incredible sense of smell and can detect a single drop of blood in a ratio of between 1:25,000,000 and 1:10,000,000,000.
We can think of evaluative abilities as emotional richness or responsiveness. Put simply, this category examines how animals use emotional responses to make "evaluative" decisions. Every emotion on the spectrum serves a purpose, so many psychologists suggest that we shouldn't label them as "good" or "bad" emotions. Still, we can assess whether a feeling will likely cause a positive or negative response.
When scientists award an evaluative score, they examine whether an animal reacts to minor changes within its internal and external worlds or whether something substantial has to happen before these creatures react.
One way to measure evaluative ability is to conduct experiments on "motivational trade-off" - does this animal have the ability to weigh the benefits of two different needs and make a conscious decision on which they choose? During one experiment, scientists gave rats access to a sweet treat, but to reach it, they had to pass through a cold chamber; the sweeter the treat, the colder the chamber. And scientists found that these rats were willing to tolerate colder temperatures to get sweeter treats. Experiments such as this suggest that rats can weigh up two scenarios and consciously choose an outcome.
Time integration is also called unity and refers to how well the left and right hemispheres of the brain work together. It is quite literally the unity of information received. For example, most of us experience sensory input as one overall stream of consciousness, but these inputs may be disunified for those experiencing split-brain syndrome.
Say you ask a person with split-brain syndrome what they see and will describe what is visible in their right-hand field of vision because the left hemisphere of the brain controls language. But, ask a person with split-brain syndrome to draw what they see with their left hand, and they will illustrate what is visible in their left-hand field of vision because the right hemisphere controls their left hand.
Integration at a time aims to define how many different conscious experiences an animal has and if these perceptions provide a unified view of the world.
Temporality or "integration across time" describes how we experience life as a linear stream of events. We capture the movement of objects in a flowing stream and do not have to try and piece together a series of events captured in static snapshots.
Still, temporality refers not only to our experience of passing time but also to an animal's ability to use dimension temporality for memory and planning. Dimension temporality can also be referred to as "time travel" or the ability to access memories of previous events and use them to help plan for the future.
For example, if an animal is looking for a suitable location to hide its food supply, can it draw on memories of where it has previously hidden food to discriminate between suitable and unsuitable locations? Taking this idea a step further, can an animal consciously "time travel" and choose to use the information to plan for the future, or is this process automated in the brain?
An awareness of the self may be one of the first criteria we consider when judging an animal's level of consciousness. At a basic level, self-consciousness involves the discrimination between self and others. At a more complex level, it is discriminating internal experiences from external ones and having the capacity to process sensory information to understand the bigger picture.
Among the more complex forms of self-awareness is the understanding that your body exists as a permanent object in the world. One way that scientists attempt to measure this is through a mirror mark test. During these experiments, the participants have a mark placed on themselves, which they can view using a mirror. They must have some self-awareness to understand that the mark is on their body. Many creatures do not pass the mirror mark test, but some who do and therefore seem to possess at least some level of bodily awareness include chimps, bottlenose dolphins, Asian elephants, and magpies.