The main reason for this dependence on behavior is that in order for any branch of knowledge to be considered scientific, we need 'proofs' and empirical or scientific evidence. The truth or reality is what you observe and considering this, behavior is the only 'observable' part of human activities so psychology, for a long time in order to be considered a science, has avoided discussions of the mind and focused on behavior. The mind is rather unknown and undefined and psychologists have thought that it is safer to avoid the mind and focus only on behavior. However the importance of behavior was primarily highlighted by the behaviorists who suggested that psychology is nothing but the study of behavior.
Behaviorism in psychology became very popular in the early 20th century and according to the behaviorist, psychology is an objective branch of natural science with no role of the mind. According to Behaviorists, all theories should necessarily have observational correlated processes, which indicate that all processes will have to be observed and that there is no difference between private and public observational processes which may be actions or feelings. This may sound a bit counterintuitive to all of us. We all consider psychology as the science of the mind rather than science of behavior however psychology has been largely influenced by behaviorism and strict scientific practices of observation, so the talk of mind has been avoided for a long time. It is only with Freud's analysis of human sexuality, and more recently with studies of consciousness, that psychology became more open about matters of the mind.
The study of behavior in psychology is thus intricately associated with the study of mind as well, as the behavior reflects whatever goes on in the mind and behavior is simply a manifestation of the mind. Let's say behavior can have an objective dimension of the personality and also a subjective dimension when associated with the mind as although our mental processes vary, our behaviors seem to have a certain standard 'core'. Thus one person may get angry in a particular situation and another person may not get angry according to subjective differences, yet the behavior of an angry person will be rather objective and standard as we all know that certain expressions represent anger. Thus there is objectivity in behavior which is why psychologists have tried to hold on to behavior for so long. We cry when we are sad, laugh when we are happy and thus there are standard behaviors or expressions of emotions which are universal across all humans and human societies. Yet the mind is complex and peculiarly individualistic and in order to describe human behavior from a more specific individualistic viewpoint, we have to consider several other factors such as social influences, genetic variations, emotions, basic drives and urges, hormonal conditions, biological variations, personality and disorders.
Thus behavior can have two distinct dimensions -
1. Objective Behavior - The more general behavior that can be universalized in the sense that certain behaviors and expressions are objective and common across cultures and societies. So irrespective of our race or genes we all have common behavioral manifestations and we all become irritated when things go wrong and feel happy when we win a game. We all cry or become distressed when we lose a loved one and express pleasure at something beautiful. There are certain expressions that are universal and common and general across all human societies.
2. Subjective Behavior - Subjective Behavior is specific individualistic behavior and varies from one person to another. This sort of behavior definitely requires an understanding of the role of the 'mind'. The mind is complex and largely specific and individualistic and no two minds are completely similar. Although our reactions and expressions to certain events and situations can be generalized and universalized, our thoughts and feelings are always unique and cannot be generalized in any way.
Considering these two divisions in behavior, the early behaviorists were actually studying the science of objective behavior rather than subjective behavior. The psychoanalysts and all non-behaviorists for that matter are concerned about subjective behavior or how subjective thoughts and feelings are manifested in behavior. Whereas objective behavior can be studied without considering the mind and by only considering certain established patterns of reactions and expressions, any analysis of subjective behavior will have to delve deeper into the mind and the wider complexities of thoughts and feelings. So let's say objective behavior is the common or general factor 'g' in all humans and the subjective behavior is the specific or individualistic factor 's' that makes every human being so unique. The 'g' is stable or a constant and found in all humans but the 's' varies and shapes individuality or uniqueness.
Of course it is important to ask why the 's' factor varies between individuals and why is it that our specific or individual natures that ultimately shape our thoughts and our behaviors are so unique. The reasons are many and one of this is our biological variations, and differences in the brain. We have different cognitive abilities our intelligence and memory vary widely so a person with very high intelligence will behave differently in a particular situation when compared with a person having lower or average intelligence. Our subjective behavior is also guided or prompted by our past experiences and memory so if a person had unpleasant experiences while traveling, he or she may show less enthusiasm for travel when compared with individuals who had better experiences. Similarly our learning and language abilities differ as also our genes and hormones so a person with overactive hormonal changes may show more hyper-reactive or high strung behavior than certain others.
Our behavior is controlled by our brain and nervous system so if there are variations with drugs, hormonal changes or certain addictions there will be a lot of difference in overt subjective behavior as well. An alcoholic or drug induced person will take longer time to process information and this affects decision making and subsequent behavior. Social influences can also affect subjective behavior as you might get influenced by newspaper or media stories or even social interactions that tend to shape behavior in a certain way. For example, television programs and news stories as well as social interactions may make you feel overweight or underweight and determine your food habits or social and personal behavior. Finally psychological disorders and illnesses and changes in the brain can affect behavior significantly and for example an autistic individual or a psychotic would behave completely differently in a situation when compared with a normal person.
The objective and subjective aspects of behavior are easily understood when you compare your own behavior with your partner's behavior. Both of you love each other and have a common expression of love but according to your subjective differences there will be differences in how you perceive your personal situation. Finally each individual is socially, genetically, biologically, psychologically attuned to behave in a certain way to a certain situation, and genes vary and so do our social exposure and influences. On winning a lottery, you may feel extremely elated like everyone else but you decide not to show your happiness. Well, this is obviously subjective and here comes the trick in psychology that although we may feel the same, we simply choose to behave differently just as we may behave in a same way although we can feel differently. This will obviously open up new debates on whether standard or general behavior, the 'g' factor is truly objective. Considering the fact that humans have to understand each other's feelings and study these through behavior, the underlying common 'g' factor would be extremely essential in decoding interpersonal behavior and this would be an essential component in successful communication and interaction across human societies. Thus in psychology it is essential to understand objective behavior as it helps to relate and communicate with others and without an underlying common factor any human interaction is not possible. However it is also necessary to understand human subjective behavior as it highlights all those peculiarities of thoughts and feelings which make every human being different and unique, a fact that is again considerably important in human society. We cannot do much without something in common but will go nowhere if we have everything in common.
