These personality traits help determine the paths people take in their environment (nurture), which in turn effects their specific behaviours. Behaviours that promoted survival in early evolution still influence the way people behave today. Evolutionary psychologists believe that evolutionary processes designed our mind for life in an environment.

They say that the human brain consists of specialized neural circuits designed by evolution to unconsciously solve problems that our ancestors faced during our evolutionary history.The scientific study of twins began in the 1870’s. Twins provide a natural control for experiments because respect for each twin’s feelings, privacy and personhood is easy for even the best intentioned scientist to compromise.

Behaviour traits such as shyness and aggressiveness cannot be inherited. Learning is a relatively permanent change in behavior or knowledge as a result of experience or practice. It comes about due to the combination of these factors: change in behavior, change in knowledge, results of experience and permanency. Learning is said to have occurred by observation of the behavior before and after learning.

Once something is learned, an organism can exhibit a behavior that indicates learning has occurred.Conditioning is the acquisition of behavior in the presence of a well defined stimulus. Classical conditioning is a type of learning in which a stimulus acquires the capacity to evoke a reflexive response that was originally evoked by a different stimulus.

Classical conditioning is the acquisition of behavior in the presence of well defined stimuli. a) Unconditioned stimulus – a stimulus that evokes an unconditioned response without any prior conditioning example food b) Unconditioned response – an unlearned reaction/response to an unconditioned stimulus that occurs without prior conditioning example salivating c) Conditioned stimulus – an originally neutral stimulus that now elicits a conditioned response example ringing the bell d) Conditioned response – behavior that the animal has learnt in response to conditioned stimulus.  Extinction is the result of eliminating the unconditioned stimulus and repeatedly presenting the conditioned stimulus alone. Eventually the conditioned stimulus will no longer elicit the conditioned response. If the conditioned stimulus and unconditioned stimulus are again paired after the conditioned response has been extinguished, the conditioned response returns to its original strength very quickly.

An extinguished conditioned response will temporarily reappear if after some time delay, the conditioned stimulus occurs without the unconditioned, this is called spontaneous recovery.Skinner are well known for researching the variables involved in operant conditioning. Operant conditioning is the process by which an organism learns a response by operating on the environment.

In operant conditioning, the focus is on operants, reinforcers and discriminative stimuli. A reinforcer is a stimulus event that increases the probability that the operant behavior will occur again. Positive reinforcers strengthen a response if they are presented after that response occurs. Negative reinforcers are the removal of unpleasant stimuli such as pain or noise. Discriminative stimuli are stimuli that signal whether reinforcement is available if a certain response is made. Stimulus discrimination occurs when an organism learns to make a particular response in the presence of one stimulus but another Primary reinforcers are events or stimuli that satisfy needs basic to survival. Secondary reinforcers are previously neutral stimuli that take on reinforcing properties if paired with stimuli that are already reinforcing. Positive reinforcers strengthen a response if they are presented after that response occurs. Negative reinforcers are the removal of unpleasant stimuli.

The effects of negative reinforcement are escape conditioning, which occurs when you learn to make a response to end an aversive stimulus and avoidance conditioning which is the process of learning responses that avoid aversive stimulus.  In one form of punishment a behavior is followed by an aversive or unpleasant stimulus. In a second form of punishment, sometimes called penalty, a pleasant stimulus is removed following a behavior.