_Attitude._ The tendency toward a particular type of response in action or a particular idea or association in thought. _Bond._ The connection established in the nervous system which makes a certain response follow a certain stimulus or a certain idea follow another idea or perception. _Capacity._ The possibility of learning, achieving, etc. _Color blindness._ Inability to experience certain colors, usually red and green. _Complementary color._ Complementary colors are those which, mixed in the right proportion, produce gray. _Congenital._ Inborn. _Connection._ The nerve-path through which a stimulus produces a response or through which one idea produces or evokes another. _Conscious._ Having consciousness, or accompanying consciousness or producing consciousness. _Consciousness._ The mental states--perceptions, ideas, feelings--which one has at any moment. _Low level of consciousness._ Conscious processes not so clear as others existing at the same time. _High level of consciousness._ Conscious processes that are clear as compared to others existing at the same time. _Contrast._ The enhancing or strengthening of a sensation by another of opposite quality. _Correlation._ The relation that exists between two functions, characteristics, or attributes that enables us, finding one, to predict the presence of the other. _Development._ The appearance, or growth, or strengthening of a characteristic. _Emotion._ The pleasure-pain aspect of experience plus sensations from characteristic bodily reactions. _Environment._ The objects and forces about us which affect us through our senses. _Environmental instincts._ Instincts which have originated, at least in part, from the periodic changes in man's environment. _Eugenics._ The science of race improvement through selective breeding or proper marriages or in some cases through the prevention of marriage. _Experience._ What we learn of the world through sensation and perception. _Fatigue._ Inability to work produced by work and which only rest will cure. _Feeble-minded._ Having important mental traits only poorly developed or not at all. _Feeling._ The pleasure-pain aspect of experience or of ideational states. _Function._ The use of a thing or process, also any mental process or combination of processes considered as a unit. _Genetic._ Having reference to origin and development. _Habits._ Definite responses to definite stimuli depending upon bonds established by use after birth. _Heredity._ Transmission of characteristics from parent to offspring. _Human nature._ The characteristics and tendencies which we have as human beings, with particular reference to mind and action. _Ideals._ Definite tendencies to act in definite ways. Ideas of definite types of action with tendency toward the actions; ideas of definite conditions, forms, and states together with a desire to experience or possess them. _Ideas._ Revived perceptions.