All that you have is at some level assumptions. Assumptions can differ only in strength, how strongly they are believed. Belief is based in mind, controlled by physical system, your body, your brain. Your brain has developed through the process of evolution where the physical system you possess is one of the physical structure that has been proven to work towards the purpose and pattern we call survival.(Proven by considering yourself alive today.)
Following heart, feelings or instinct, another way of saying that you give in to ancient evolutionary patterns, which through the reflection of time prove itself worthy relying towards the unknown destination we often call survival.
Impulses adapts us to the physical memory of our environment. Your past connects to the past of this world. You relying on the memory of the physical, part of the world, a formation generated from the creation of life to the being you are now. The memory we call DNA, encoded as self replicating documentation of past experiences, emergent from change happening through time.
Complexity gave us the ability to choose. Tempting behavioural patterns that this world has limited us to through physical are what we call biases. They are sets of patterns in your brain which reacts in specific ways to specific situations, giving rise to predictable behaviours.
“Sensations”, physical impulses traveling through system of matter, which through it’s pattern of movement observes itself and thus reflects. Consciousness, thus an emergent effect from physical arrangement.
To be biased means to be prone to perform certain processes over others. The existence of biases can be simply confirmed by observing that we are beings of memorisation and adaption, in other words systems of learning. we are both patterns seekers and pattern consumers. We have now through what we call our selves, our learning pattern, measured our learning pattern.