Introduction to Cognitive Psychology: Sensation, Perception, and Attention

Introduction to Cognitive Psychology

Definition of Cognition and Cognitive Psychology

Block 1. Part 1. Introduction: Integrated aspects of the course.

1. Definition of cognition and cognitive Psychology.

   Cognition: refers to all processes by which knowledge is acquired and manipulated. Cognitive Psychology: study of mental processes or cognitive processes and functions. Developed thanks to Max Wertheimer (gestalt theory), Jean Piaget (cognitive development), and Noam Chomsky (language/mental processes). Provide a theoretical description of the mind & find quantitative evidence on mental functioning. Mental processes: all processes underlying overt behaviours, internal process

   • Basic mental process: involved in acquiring and storing knowledge

     Sensation Perception Attention Emotions Language

   • Complex mental process: cognitive processes that require you to already know or remember something in order to work.

     Thought Memory Metacognition Symbolic Function Intelligence · Behavior

Sensation, Perception, and Attention Definitions

1. The definition of sensation, perception, and attention.

   Sensation: process by which our body detects and converts external or internal stimuli into neural signals, which are then sent to the brain for interpretation. Senses: allow us to process physical stimuli so we can perceive them.

   • Sight
   • Hearing & Balance
   • Taste
   • Smell (olfactory)
   • Somatosensory system

     Perception: organizing and interpreting sensory information, recognizing meaningful events.

The Sensory Perceptive Process

3. The sensory perceptive process

• involves receiving and sending stimuli and its ulterior interpretation

  Stimulus: energy change which is registered by senses Sensory receptor: sensory nerve ending that responds to a stimulus i n the internal or external environment. Distal stimulus: stimulus at a distance, specified in terms of its physical characteristics. Proximal stimulus: stimulus in proximity to the receptor, image we create in the receptors of our retinas. Condition for sensoperceptive process:

  • Physiological:

    Stimuli: provide energy for perception Organs: receive stimuli, transform into nervous impulses Transmitting organs: send nerve impulse to brain Analysis, synthesis, and control centers

  • Psychological:

    Conservation and reproduction of past experiences through memory. Intellectual elaboration of the info. Depends on different intellectual processes such as association with other experiences or stimuli, abstraction, generalization, etc. Different phases of the sensory-perceptual process: Environmental Stimulus -> Attended stimulus -> Stimulus on the Receptors -> Transduction -> Processing -> Perception -> Recognition -> Action Environmental stimulus: all elements in the environment that we can potentially perceive. Attended stimulus: a specific part of the environmental stimuli, our attention is on this part. How receptors work

  • Cells in the eye's retina capture light and change it into electrical energy
  • Retina: receives image produced by lens, continuous with optic nerve, consists of several layers (rods and cones sensitive to light)

    Neural processing: operations transforming the neural electric signals

  • The image of an object travels as sensory information through the optic tracts to the thalamus and to the visual cortex where it is interpreted.

    Processing and Perception depend on knowledge: It includes:

    1. Recognition and inclusion of the stimulus in different categories
    2. The individuals action based on perception
    3. Previous knowledge about the environmental stimulus

       Recognition: our ability to place an object in a category Action: follows perception and recognition. Important outcome of the perceptual process because its importance for survival. Bottom-up processing: stimuli-driven because it is directly affected by stimulus input. Up-down processing: conceptually driven as it is affected by existing knowledge.

Defining Attention

1. The definition of attention

   Attention: our capacity to actively and also passively focus on the environmental and internal world.

   • Selective dimension

     Selective attention: processing different stimuli and just responding to one of them. (SELECTION) Divided attention: processing different stimuli and responding to more than one. (CAPACITY)

   • Intensity dimension

     Sustained attention: persistence of performance throughout time. (VIGILANCE)

Historical Tour on Sensation and Perception

Theoretical Approaches in Sensation and Perception

Block 1. Part 2. Historical tour on sensation and perception: philosophy, psuchophysics, and physiology

1. Theoretical approaches in the study of sensation and perception

   Greek philosophers wondered how much we could trust our senses to acquire knowledge: RATIONALISM vs. EMPIRICISM

   • Rationalism: knowledge is acquired through reason, without the aid of the senses

     Plato

     • Senses are not a reliable source of knowledge
     • Real knowledge involves reasoning.

       Descartes

     • Human intellect is able to perceive the nature of reality through a purely intellectual perception ("I think, therefore, I am")
   • Empiricism: knowledge comes to human being through sensations

     Aristotle

     • Senses are essential for accurately determining reality

       John Locke

     • Our mind is a "tabula rasa" or "blank slate"

       Constructivism: prior knowledge is essential for integrating sensory data, we ue existing knowledge to make sense of sensory information Kulpe (1904): Cognitive experiences are active mental processes where we interpret sensory or intellectual content, shaped by our knowledge and mental state.

   Structuralism: seeks to analyze the elements of mental experiences.

   • Helmholtz, Wundt, and Titchner, 19th century
   • The mind is built from a collection of basic sensory experiences

     Gestalt approach:perception is not just a passive process but an adaptive tool for survajival and evolution. "The whole is more than the sum of the parts"

   • Wertheimer, Koffka, and Köhler

     Ecological approach: real existence of objects is directly perceived

   • James Gibson
   • We don't need complex internal processes to make sense of what we see.
   • The information we receive through our senses is sufficient for us to perceive the environment accurately.

Methodological Approaches in Sensation and Perception

1. Methodological approaches in the study of sensation and perception

   Psychophysics: Study of the relationship between the stimulus (physiscs) and perception (psycho) Weber & Fechner (created psychophysics)

   • Conceive sensation as a mental fact

     Created experimental procedures so to analyse perceptions based on sensations

   • Focused on thresholds

     Absolute threshold: smallest amount of energy necessary to detect stimulus

     • Vision: a candle flame 40km away
     • Hearing: a watch ticking 6 meters away
     • Olfaction: a drop of perfume in a six-room house
     • Touch: a wing of a fly on your cheek, dropped from 1 cm

       Detecting Absolute Thresholds

       1. Method of Limits
       2. 2nd most precise
       3. The experiment presents stimuli in either ascending or descending order
       4. Observer indicates by a "yes" if they perceive the stimulus
       1. Method of Adjustment
       2. First estimation of absolute threshold
       3. Fastest method
       4. Experimenter adjusts stimulus intensity continuously until the observer can just barey detect the stimulus
       5. Observer doesn't have to say anything, simply has to adjust intensity until they can just barely hear the tone
       1. Method of constant stimuli
       2. Experimenter presents 5 to 9 stimuli with different intensities in random order
       3. Most accurate method

          Detecting Difference Threshold Difference threshold (DL): smallest difference between two stimuli that a person can detect. The size of the DF depends on the standard weight

       4. Greater standard weight -> Greater DL
       5. The ratio of the DL to the standard stimulus is constant:

          This is called Weber's Law: DL/S=K

          • K: Weber fraction
          • S: value of the standard stimulus
          • DL: the difference threshold

            Wever fractions for different sensory dimensions. We can see that people can detect 1 percent change in the intensity of an electric shock, but that light intensity must be increased by 8 percent before they can detect a difference. Methods for magnitude estimation Magnitude: perceived intensity or strength of stimulus Magnitude estimation: a psychophysical scaling technique where a participant assigns numerical values to a stimulus based on its perceived magnitude.

   • Procedure:

     Experimenter presents standard stimulus, assigns it a value of 10. Experimenter presents stimulus of different intensity. Observer asked to assign number to new intensity. If twice as intense -> 20 If half as intense -> 5

   • Red Curve - Magnitude Estimation of Brightness

     A study measured how people perceive brightness as light intensity increases. Key finding: Perceived brightness does not increase as quickly as actual intensity. For example:

     • Intensity 20 -> Perceived brightness = 28
     • Intensity 40 -> Perceived brightness = 36 (not double)

       This effect is called response compression:

     • As intensity increases, perceived brightness increases more slowly.
     • To double perceived brightness, the intensity must be multiplied by about 9.

   80 70 60 Magnitude estimate 50 40 30 -Brightness 20 -- Line length 10 -Electric shock 0 0 10 20 30 40 50 60 70 80 90 100 Stimulus intensity

   • Orange Curve - Magnitude Estimation of Electric Shock

     This experiment measured how people perceive the intensity of an electric shock. Key finding: Perceived shock increases faster than the actual intensity. For example:

     • Intensity 20 -> Perceived sensation = 6
     • Intensity 40 -> Perceived sensation = 49 (much more than double)

       This effect is called response expansion:

     • As intensity increases, perceived sensation increases more rapidly.
   • Green Curve - Magnitude Estimation of Line Length

     This experiment measured how people perceive the length of a line. Key finding: Perceived length increases in direct proportion to actual length. The curve is straight with a slope of 1.0:

     • Doubling the line's length -> Perceived as twice as long.

       This shows a linear response: perception matches stimulus intensity. The relationship between the intensity of a stimulus and our perception of its magnitude follows the same general equation for each sense. These functions are called power functions.

     • Steven's power law -> P=KS^n

       P: perceived magnitude

     • K: constant
     • S: stimulus intensity
     • n= power, depends on type of stimulus