Lifestyle may also vary, noting still, it's relevance with culture. Culture involves spirituality, traditions, customs, attitudes, beliefs, and behaviours, serve as filters through which the person may respond to its surroundings. Another of the potential sources of error and bias in the development and application of intelligence tests is the ongoing debate of whichever is more influential, heredity or environment - nature vs. nurture. In this aspect, the validity of the test is also affected, thus affecting its development and application. With such controversies continuing, the tests are still in use, but not anymore the sole determiner of the child's mental and emotional abilities and conditions ("Intelligence Tests").
Theories of personality have a widespread interest among most schools of psychology and had contributed many ideas in this field of psychology. Freud's theory on personality centres more on the human sexuality, whereas psychologists such as Jung and Horney may beg to differ. However, when it comes to contemporary theories of personality, it is usually connected to intelligence. The cognitive aspect of personality is popularized by Carl Jung. In this theory, it states that by changing our thoughts, it follows that we change our moods, our anxiety, and the state of our relationships. With such, an individual tends to decrease his or her anxiety, and even improve their relationships with others (Heffner). Personality according to other psychologists, deals only with one's emotions, especially needs as individuals in terms of the physiological nature, as well as the emotional nature. However, most of them have failed to see how the mind or the cognitive aspect affects personality - seeing it as a very strong influence on one's emotional and physiological needs. The mind is a very powerful thing - as the saying goes, "mind over matter" - wherein the mind can literally control a person's emotions by justifying or rationalizing any event or circumstance that the person might be going through. A similar effect goes for a person's perception to actually increase or decrease his or her anxiety on a situation - depending on how he or she might perceive it.
3. Compare and contrast theories equating intelligence either with "mental speed" or "working memory".
Mental speed may be characterized by the person's ability to calculate ideas, or come up with ideas but may not necessarily mean that high level of intelligence is the basis for such. Working memory, on the other hand, requires the individual the ability to understand spoken sentences, or remembering a string of numerical digits. In this aspect, intelligence is based on the individual's ability to process information, requiring efforts mentally. Mental speed is too, requiring intelligence. However, a person who is very much familiar with a certain idea, or topic may be faster in speed, compared to the other who may not be as familiar with it. However, familiarity to something doesn't measure level of intelligence.
4. Appreciate the relationship between theory and assessment of individual differences.
An individual difference is the fact that not all humans are alike - exactly.