mental models are modified to match concrete objects or situations (Perlovsky, 1987; 2001; 2006a; Bar, Kassam, Ghuman, Boshyan, Schmid, Dale, Hämäläinen, Marinkovic, Schacter, Rosen, and Halgren, 2006).

How these cognitive processes are determined and affected by language? Primate"s cognitive abilities are independent from language. Language is fundamental to human cognitive abilities (Perlovsky, 2006a). A possible mathematical mechanism of language guiding and enhancing cognition have been discussed in (Perlovsky, 2004; 2006a,c; 2007a,b; 2009a,b; 2010d,g,m; Fontanari & Perlovsky, 2005; 2007; 2008a,b; Fontanari, Tikhanoff, Cangelosi, Perlovsky, & Ilin, 2009). This is a mechanism of the dual model whereby every concept-model has two parts: cognitive and language. The language models (words, phrases) are acquired from surrounding language by age of five or seven. They contain cultural wisdom accumulated through millennia. During the rest of life the language models guide the acquisition of cognitive models.

## 2.3 Emotions, Instincts, And The Knowledge Instinct

The word emotion refers to several neural mechanisms in the brain (Juslin & Västfjäll, 2008); in this paper I always refer to instinctual-emotional mechanism described in (Grossberg & Levine, 1987). The word instinct in this paper is used in correspondence with this reference to denote a simple inborn, non-adaptive mechanism of internal "sensor," which measures vital body parameters, such as blood pressure, and indicates to the brain when these parameters are out of safe range. This simplified description will be sufficient for our purposes, more details could be found in (Grossberg & Seidman 2006; Gnadt & Grossberg, 2008) and references therein. We have dozens of such sensors, measuring sugar level in blood, body temperature, pressure at various parts, etc.

Mechanisms of concepts evolved for instinct satisfaction. According to instinctual-emotional theory (Grossberg & Levine, 1987), communicating satisfaction or dissatisfaction of instinctual needs from instinctual "sensors" to decision making parts of the brain is performed by emotional neural signals. Perception and understanding of concept-models corresponding to objects or situations that potentially can satisfy an instinctual need receive preferential attention and processing resources in the mind. In this paper emotions refer to neural signals connecting conceptual and instinctual brain regions. 

Perception and cognition requires matching top-down signals from concept-models to bottom-up signals coming from sensory organs. Perception is required for survival. Therefore humans and high animals have an inborn drive to fit top-down and bottom-up signals, the knowledge instinct (KI; Perlovsky & McManus, 1991; Perlovsky, 1997; 2000; 2006a; 2007a). These references discuss specific emotions related to satisfaction or dissatisfaction of KI. These emotions are related purely to knowledge, not to bodily needs; since Kant (1790) this type of emotions are called aesthetic emotions. According to the theory of KI they are inseparable from every act of perception and cognition.

Biologists and psychologists have discussed various aspects of this mechanism: a need for positive stimulations, curiosity, a motive to reduce cognitive dissonance, a need for cognition (Harlow & Mears, 1979; Berlyne, 1960; Festinger, 1957; Cacioppo, Petty, Feinstein, & Jarvis, 1996; Levine & Perlovsky, 2008). Until recently, however, this drive was not mentioned among "basic instincts" on a par with instincts for food and procreation. The fundamental nature of this mechanism became clear during mathematical modeling of workings of the mind. Our knowledge always has to be modified to fit the current situations. We don"t usually see exactly 