________________________________________________: emotions are subjective reactions to the environment, usually accompanied by some form of physiological arousal and expressed in some form of behaviour. Smiling and laughter are the first expression of pleasure: infants show preferences for human faces. Duchenne smiles are special smiles an infant makes for their mother: not all babies smile with equal frequency; individual, cultural, and sex differences exist (ex. girls smile more than boys). Theoretical perspectives on emotional development: genetic-maturational perspective: emotions are best seen as products of biological factors, twin research shows that identical twins show more of a similarity in emotions than fraternal twins, supporting the biological basis of emotion. Learning perspective: individual emotional expression result from individual experiences: experiences elicit and reinforce responses, functionalist perspective: emotions serve to help us achieve our goals and adapt to our environment, emotional signals (social cues) guide behaviours.