Comprehensive Study Guide for Cognitive Psychology and Psychophysics

Attention and Visual Perception Mechanisms

Attention stability is estimated through the duration of concentration on a specific aspect of a situation. It represents the temporal maintenance of focus without susceptibility to external distractors or mental shifts. Within the context of visual recognition, particularly the 3D model proposed by Marr and Nishihara, several criteria allow for object constancy. Sensitivity is the criterion that enables the recognition of an object, such as a parrot, regardless of the observer's viewing angle. Marr’s computational model outlines a specific sequence of stages in visual perception, starting with the primal sketch, which involves basic feature detection like contours and light/dark contrasts. This is followed by the 2.5D sketch (or intermediate sketch), which details distance and orientation of surfaces relative to the viewer. The final stage is the 3D model representation, which is an object-centered description allowing for recognition from any perspective.

Biederman’s (1987) recognition-by-components theory suggests that objects are recognized via primitive geometric shapes known as geons. The process involves specific stages: extracting contours, detecting non-accidental properties (such as symmetry or parallelism), segmenting the object into sectors with concavities, and determining the geon components. After the geons are determined, the subsequent step is matching these components with the stored representations of objects in memory. This theory posits that recognizing an object is contingent on identifying its constituent geon parts at their points of intersection.

Perceptual constancies are fundamental to maintaining a stable view of the world. Color constancy allows for the perception of light radiation of different wavelengths as invariant even when environmental lighting changes. Similarly, brightness constancy ensures objects maintain the same ratio between their light intensity and the projected area regardless of light levels. Size constancy ensures objects are perceived as the same size despite changes in the retinal image size due to distance. Depth perception relies on several cues; for distant objects, linear perspective (parallel lines converging at the horizon) and texture gradients provide depth. Motion parallax, where closer objects appear to move faster than distant ones, also serves as a monocular cue. The accommodation of the lens provides information about the proximity or distance of near objects. In the study of face recognition, Young, Heltawell, and Hay (1987) demonstrated the "composite effect," where matching two halves of different celebrity faces makes identifying each half difficult when aligned, but recognition of the upper half is significantly improved when the composite face is inverted, breaking the holistic processing.

Sensory Thresholds and Psychophysics

Psychophysics explores the relationship between physical stimuli and psychological sensations. The absolute threshold is the lowest intensity of a stimulus that can be registered by the senses, influenced by an individual's physical state, learning, and previous experience. The differential threshold, or Just Noticeable Difference (JND), is the smallest detectable difference between two stimuli that can be perceived in at least half of the cases. This follows Weber's Law, which states that the JND is a constant proportion of the original stimulus intensity. For weight, the Weber fraction is approximately $1/30$. Therefore, if a person carries a bag weighing $7\text{ kg}$ ($7000\text{ g}$), the minimum amount of weight needed to perceive a difference is calculated as:

$7000 \times \frac{1}{30} = 233.33\text{ grams}$

Similarly, different modalities have different constants: light intensity has a fraction of $1/100$, and sound intensity has a fraction of $1/10$. If a room has a light source of $1000\text{ lumens}$, the required addition to notice a change in intensity for half of the subjects is:

$1000 \times \frac{1}{100} = 10\text{ lumens}$

If a sound source at a concert is $200\text{ watts}$, the increase needed to feel an observable difference is:

$200 \times \frac{1}{10} = 20\text{ watts}$

Sensory qualities are defined by physical properties. Chromatic tone in visual sensations is determined by the wavelength of the light. Saturation is determined by the amount of white light mixed into the color, while brightness is determined by the amplitude of the light radiation. In audition, the intensity of sound waves is determined by the amplitude of vibrations, while pitch is determined by the frequency of vibrations. The protypical cortical projection for gustatory (taste) sensations is located in the foot of the postcentral circumvolution (specifically within the opercular-insular cortex).

Memory Architecture and Processes

Memory is conceptualized as a multi-store system following Atkinson and Shiffrin (1968). Information first enters the sensory register (sensory memory), where it persists for approximately $1/4$ of a second. Short-term memory (STM) stores physical qualities and has a limited capacity typically defined by George Miller's "Magic Number" of $7 \pm 2$ elements. Capacity in STM can be increased through chunking or grouping materials into units. In contrast, long-term memory (LTM) is organized primarily by categories of meanings (semantic codes) rather than physical features and is highly durable. Craik and Lockhart (1972) challenged the idea of separate storage zones, proposing the "Levels of Processing" framework, where the duration of material persistence depends on the depth of processing; semantic processing (focusing on meaning) is more efficient than structural or phonological processing.

Memory is further subdivided into declarative and non-declarative (procedural) systems. Declarative memory includes episodic memory, which stores specific experiences defined by space and time (e.g., "When I was in Tokyo, the cherry trees were in bloom"), and semantic memory, which stores general knowledge, meanings, and facts (e.g., "Karate is a Japanese fighting style") without temporal-spatial reference. Paivio’s Dual Coding Theory suggests that declarative memory contains both verbal and non-verbal/imagistic systems that are interconnected yet distinct; memory performance is generally better when information is coded both analogically (images) and verbally. Procedural memory involves skills and actions acquired via conditioning or repetition and is often accessible only through action. Research by Anderson (1983) suggests that while verbal and visual materials are stored in different brain areas, their storage mechanisms are similar.

Working memory involves the "Central Executive," which acts as the administrator responsible for shifting attention between tasks, inhibiting irrelevant information, and coordinating the phonological loop and visuo-spatial sketchpad. Forgetting occurs through various mechanisms. Decay theory (or trace erasure theory) suggests forgetting happens simply because time passes; this theory is best verified for sensory registers and working memory. Interference theory posits that memory is disrupted by similar information; retroactive interference occurs when new learning disrupts the recall of previously learned material. Motivated forgetting, popularized by Sigmund Freud as repression, occurs when the mind unconsciously pushes unpleasant or threatening information out of consciousness to protect the individual.

Language Development and Conceptual Thinking

The acquisition of language involves the combination of cognitive abilities, motor skills, and social interaction. Development follows specific milestones: phonetic expansion occurs around $6-7$ months, and telegraphic speech (two-word sentences) typically manifests between $18-24$ months. Children acquire grammatical morphemes in a consistent order; for example, they usually acquire the possessive pronoun before conjugating verbs and immediately after acquiring the plural form. Theoretical perspectives on language and thought vary. Watson and Wittgenstein (in some interpretations) argued that thought is essentially linguistic. Vygotsky emphasized the social origins of language, viewing children's "egocentric speech" as a tool for problem-solving that eventually becomes internalized. Piaget argued that language develops from the need to communicate but is preceded by sensorimotor intelligence.

Conceptual organization is often explained through Prototype Theory, which assumes that every category has a "best example" or prototype that possesses a collection of specific attributes. Category membership is determined by the degree of similarity between a new object and this prototype. Eleanor Rosch identified three levels of categorization: superordinate, basic, and subordinate. Basic-level concepts (like "chair" or "apple") are the most functionally useful because their members have similar shapes, require similar motor movements, and are easily named. Conjunctive concepts are defined by the simultaneous presence of two or more common characteristics. In problem-solving, humans utilize heuristics—mental shortcuts such as the representativeness heuristic (deciding based on similarity to a prototype) or the availability heuristic (deciding based on how easily information comes to mind).

Emotion, Motivation, and Personality

Emotions are complex affective states often categorized by their origin and function. Robert Plutchik’s evolutionary theory views emotions as innate behavioral patterns with eight basic emotions. He describes "dyads," which are mixtures of basic emotions; for instance, the primary dyad resulting from the association of sadness and disgust is regret or remorse. Plutchik's model includes five components: stimulus, cognition, feeling evaluation, behavior based on innate mechanisms, and the function served by the behavior. The Cannon-Bard theory argues that emotional experience and physiological changes occur simultaneously and independently. Schachter's cognitive theory (Two-Factor Theory) posits that the interpretation of the stimulus—and the labeling of physiological arousal—is what produces the specific emotion, leading to possible misattributions of arousal.

Motivation can be intrinsic, where an individual performs an action for its own sake (e.g., an anonymous donation), or extrinsic, driven by external rewards. Physiological needs like hunger are regulated by the hypothalamus (specifically the lateral and ventromedial centers), blood glucose levels, and lipid levels. Personality theories differ in their view of human nature. Skinners’s behaviorism is strongly environmentalist, while George Kelly’s Personal Construct Theory emphasizes that individuals are like scientists who test hypotheses about reality using subjective constructs; these constructs are bipolar and can be modified. Freud’s psychoanalytic theory, characterized by defense mechanisms like projection and rationalization (which involve modifications of perceived reality), has been criticized for its low empirical verifiability.

Clinical Conditions and Discussion

Cognitive deficits provide insight into normal brain function. Optic aphasia is a condition where patients can use an object (like a hammer) correctly, demonstrating that their functional knowledge is intact, yet they struggle to name the object when seeing it. This is distinct from visual agnosia, where the perceptual recognition itself is impaired. Prosopagnosia is a specific deficit in recognizing familiar faces. Within the context of psychopathology, schizophrenia is diagnosed when an individual persistently exhibits false ideas (delusions) and distorted sensory experiences (hallucinations). Discussions in the field also address the efficiency of self-attribution in academic settings; external, unstable attributions for failure (e.g., "the test was unusually hard this time") are considered more effective for protecting self-esteem and maintaining motivation compared to internal, stable attributions (e.g., "I am not smart enough")."