TESIS DOCTORAL - Robotics Lab - Universidad Carlos III de Madrid

24 Chapter 2. Biological foundationsThe ecological constrains and the anticipatory mechanisms [50], and the drive reduction[52], somehow, all are related to physiological needs. The hedonic factor in motivatedbehavior is clearly identified in both approaches.Since pleasure is an evident element on motivated behavior, researchers have studiedhow it is evoked. Olds [61] discovered pleasure areas on animal’s brain. Later, Deutschand Howard [62] found that stimuli of pleasure areas on the brain originate reinforcementindependently of the drive state of the animal. In contrast, regular stimuli just function asreward in particular states (food is considered as reward just in hungry animals). Successivestudies have shown that pleasure areas in the brain are involved on initiating some complexbehaviors such as feeding and drinking. Apparently hypothalamus is one of the areas thatproduces reward and several transmitters seem to take part.2.4 EmotionsThus far, emotions have not been mentioned. However, emotions play a key role in thebehavior exhibited by people and animals. Emotions are essential in our daily live. Theymake us going high and low in all our experiences. Emotions are not easy to study and justtheir behavioral manifestation can be certainly observed. Besides, emotions are not exclusivefrom humans [63], it is proved that animals also are endowed with emotional states[7]. Actually, Charles Darwin (1809-1882) studied emotions in humans and animals justby observation of the emotional expressions during his trips to exotic places. His evolutionarytheories suggested that emotions have evolved due to their efficacy for adaptationand for communicating the behavioral intention, and, also, their role in social interaction[64]. Currently, it is widely accepted that humans and mammals share some emotionalbrain regions [54].2.4.1 The role of emotionsEmotions are versatile mechanisms which are involved in many functions. According toRumbell [65], emotions influence the attention, alter the likelihood of behavioral responses,activate associative memories, arrange rapid responses, influence learning, aid social behavior,and improve communication.In this thesis, the attention is directed to the influence of emotions on the decisionmaking process and the learning process. Cañamero states that emotions and motivationsplay a main role in autonomy and adaptation in biological systems [66].According to the popular belief, emotional reactions are undesired and not appropriated.In contrast, rational reaction are more appreciated. However, both reactions are requiredand have different functions. Reason and emotions separately can make wrong decisions.A reasonable action can be rated as inadequate (to kill a person in order to save many),