This question asks to identify the correct assertions related to Carl Rogers' influential theory of personality. Rogers, a key figure in humanistic psychology, emphasized personal growth and self-actualization. Let's analyze each statement based on his core concepts.

Assertion Analysis in Rogers' Theory

A: Self-actualisers are the healthiest one percent of the population.

Carl Rogers believed strongly in the concept of self-actualization, describing it as the innate human drive towards fulfilling one's potential. While he viewed self-actualized individuals as representing optimal psychological health, he did not specify a precise numerical percentage, like "one percent," to define them. This specific quantification isn't a direct tenet of his theory, making this statement questionable in its exact wording.

B: The perceived self influences both the person's perception of the world and his or her behaviour.

This assertion aligns well with Rogerian principles. The 'perceived self', often referred to as the 'self-concept', is central to Rogers' theory. It represents how individuals see themselves. According to Rogers, this self-concept acts as a filter through which experiences are interpreted. Therefore, the way we perceive ourselves directly impacts how we see the world around us and consequently guides our actions and behaviour. This is a fundamental aspect of his phenomenological approach.

C: People are likely to function more effectively if they are brought up with unconditional positive regard.

This statement is accurate according to Rogers. He highlighted 'unconditional positive regard' (UPR) as a crucial element for healthy psychological development. UPR means being valued and accepted completely, regardless of one's behaviour. When individuals receive UPR, especially during childhood, they are more likely to develop a congruent self-concept, where their experiences align with their sense of self. This congruence fosters openness, reduces defensiveness, and promotes more effective functioning and self-actualization.

D: Each of us has an ideal self.

Rogers indeed differentiated between the 'real self' (who we actually are) and the 'ideal self' (who we aspire to be). The ideal self represents our goals, values, and desires for who we want to become. Rogers suggested that the degree of congruence or discrepancy between the real self and the ideal self significantly impacts an individual's psychological well-being. A closer match generally indicates better adjustment, while a large gap can lead to distress.

E: Individuals, whose self-concepts match their feelings and experiences, must defend themselves against the truth.

This statement contradicts Rogerian theory. Rogers proposed that individuals who experience congruence – meaning their self-concept accurately reflects their experiences and feelings – are typically open to experience. They do not need to distort reality or defend themselves against threatening information. Instead, defensiveness arises when there is incongruence, where experiences contradict the existing self-concept, leading individuals to deny or distort reality to maintain self-esteem.

Conclusion on Assertions

Based on the analysis, assertions B, C, and D accurately reflect key concepts within Carl Rogers' theory of personality. Assertion B highlights the influence of the perceived self on perception and behaviour. Assertion C emphasizes the importance of unconditional positive regard for effective functioning. Assertion D correctly states the existence of an ideal self in Rogers' framework. Assertions A and E are inconsistent with his core ideas.