Sensation, Perception and Attention: Cognitive and Neurophysiological Processes

Cognition and Cognitive Psychology

Cognition: all processes are acquired by which knowledge is acquired and manipulated. Its ability to access knowledge.

Cognitive psychology: studies mental processes or cognitive processes and functions.

Sensation: Biophysical Process

Sensation: arises from an environmental bodily stimulus that reaches the senses. Its a biophysical process in charge of receiving information from outside or the inside(inputs), transforming it and codifying into neural impulses and sending it to the brain for decoding. The brain analyzes this information and attributes a meaning

• Senses: Senses are neurophysiological systems that allow us to process physical stimuli (sensory information) and process them so we can perceive them. The brain receives input from the sensory organs

Perception: Neurocognitive Function

Perception: information is received, it will be processed and interpreted in specialized areas of the brain to allow the organism to respond in a conscious way to incoming stimuli. Perception isa neurocognitive function. It consists of the organization, identification, and interpretation of sensory information. The brain makes sense out of the input from sensory organs

• The brain makes sense out of the input from sensory organs
• The differences between sensation and perception Perception, process construction, both expectations and previous knowledges intervene, interpretation Sensation, immediate nature, simple and isolated events, response executed by our senses in response to a stimulus

The Sensoperceptive Process

The sensoperceptive process This involves receiving and sending stimuli (physiological process) and its ulterior interpretation (psychological process) Stimulus, this is the energy change which is registered by the senses Sensory receptors, sensory nerve ending that responds to a stimulus in the internal or external environment

Phases of the Perceptual Process

Different phases of the perceptual process Distal stimulus is simply the stimulus at a distance (it is specified in terms of its physical characteristics) Proximal stimulus is simply the stimulus in proximity to the receptors (image we create in the receptors of our retinas)

Conditions for the Sensoperceptive Process

The sensory perceptive process and the conditions for the sensoperceptive process Physiological

• Stimuli, which provide the energy for perception which may come from the external environment or from the organism
• Organs, these receive the stimuli and transform them into nervous impulses
• Transmitting organs which send nerve impulses to the brain
• Analysis, synthesis and control centersThe areas in which the cerebral cortex is the signal analysed, selected and associated and the information is recognised Effector areas, in which they respond in organised and transmitted to the agency for execution

Psychological Conservation and reproduction of past experiences through memory. Intellectual elaboration of the information. It depends on different intellectual processes such as association with other experiences or stimuli, abstraction, generalisation

Environmental and Attended Stimuli

Environmental stimulus and attended stimulus Environmental stimulus, All these elements in the environment that we can potentially perceive This can be anything we can possibly sense Attended stimulus is a specific part of the environmental stimuli We focus our attention on this specific part

How Receptors Work

How receptors work Cells in the eyes retina capture light and change it into electrical energy The retina is the innermost coat of the posterior part of the eyeball that receives the image produced by the lens, is continuous with the optic nerve, and consists of several layers, one of which contains the rods and cones that are sensitive to light.

Transduction Process

Transduction The fluid inside the neurons consists of water and ions (atoms electrically charged) which move in and out through the ion channels (microscopic pores). If many ion channels open, they can create a wave of electric energy or action potential that runs down an axon Cells in the eye's retina capture light and change the light energy into electrical energy. These waves can travel very fast. (potentially 432 kms per hour)

Neural Processing and Perception

The neural processing Operations transforming the neural electric signals Perception: how you arrange the information Trying to figure out the sensation. Processing and perception depend on knowledge which include

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

Recognition and Action

Recognition: place the stimulus into a category. This is our ability to place an object in a category Perception and recognition are different processes (the individual with this brain damage can see things well but have a very difficult time recognising what they are) Action : Action follows perception and recognitionSome researchers see action as being an important outcome of the perceptual process because its importance for survival

Milner and Goodale's Perspective

Milner and Goodale Early in evolution of animals the major emphasis of visual processing was not to create a conscious perception but to help the animal control navigation, catch prey, avoid obstacles and detect predators

Role of Knowledge and Representations in Perception

The role of knowledge and representations on perception According to cognitive psychology, previous knowledge and mental representations are essential for perceiving stimuli In order to succeed at recognising a particular stimulus we compare sensory clues with our previous concepts and representations. These concepts are stored in long term memory, these are essential for understanding the meaning

Bottom-up and Top-down Processing

Bottom-up and top-down processing Bottom-up processing, it is stimulus-driven because it is directly affected by the stimulus input Up-down processing, it is conceptually driven and it is affected by existing knowledge derived from past experience. For instance, Listening to a conversation in an empty room. Our brains are not empty at all, they are full of knowledge, memories, expectations

Attention: Neurocognitive Function

Attention This is the neurocognitive function which consists of our capacity to actively and voluntarily and also passively and involuntarily focus on the environmental and internal world. Thanks to attention, we select the most relevant stimuli and relate them with previous information

• Attention precedes our perception and action, operating on all the present stimuli that we find at a specific moment
• It operates filtering the signals that appear while we are awake and directing our interest towards a specific source of simulation

Dimensions of Attention

There are two basic dimensions of attention depending on its intensity or selective nature Vigilance, Sustained attention, persistence of performance throughout time Selection, selective attention, processing different stimuli and just respond to one of them Capacity, divided attention, processing different stimuli and responding to more than one Vigilance is the intensity dimension Selection and capacity is the selective dimension

Philosophy, Psychophysics and Psychology

from ancient Greece (4th century b.c) philosophers have wondered to what extent our senses provide us with a valid knowledge of the world around us. Greek philosophers wondered how much we could trust our senses to acquire knowledge

Rationalism vs Empiricism

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: Aristoteles

• Knowledge comes to human beings through sensations.
• Senses are essential for accurately determining reality. John Locke (17th century). Our mind is a "tabula rasa":
• the theory that at birth, the (human) mind is a "blank slate" withoutpre-existing rules for processing data. These rules are forme and knowledge is acquired solely through sensory experiences.

Constructivism in Cognitive Experiences

Constructivism: Prior knowledge is essential for integrating sensory data. We use existing knowledge to make sense of sensory information. Kulpe (1904): Cognitive experiences are best described in terms of occurring cognitive acts or attitudes toward sensory, imagistic, or intellectual contents.

• They reflect how we actively engage with and interpret the world, influenced by prior knowledge and mental states

Structuralism vs Gestalt Approach

Structuralism vs gestalt Structuralism (Helmotz, wundt and titchner) Seeks to analyze the elements of mental experiences, such as sensations, mental images, and feelings, and how these elements combine to form more complex experiences. Method: Introspection. The mind is built from a collection of basic sensory experiences.

• Gestalt approach (wertheimer, Koffka and Köhler) Anti-structuralist vision= interest in the phenomenological perceptual experience as a whole. Perception is not just a passive process but an adaptive tool for survival and evolution. It cannot be broken down into its basic elements. It is a dynamic process where we organize data into meaningful patterns.
• Method: experiments to demonstrate how we perceive and organize inputs into coherent wholes.

Ecological Approach to Perception

Ecological approach James Gibson (1950): he believed that the real existence of objects is directly perceived (Theory of direct perception)

• Gibson defends direct realism as opposed to the indirect realism of cognitive psychology Gibson seeks to clarify how our visual system maintains an accurate perception in spite of the constant shift in information it gets. Complicated internal procedures are not necessary for us to interpret what we observe. Our senses provide us with enough information, particularly visual information, to enable us to accurately perceive and comprehend our surroundings.

Methodological Approach in Sensation and Perception

Methodological approach in the study of sensation and perception Psychophysics (weber and fechner) = created: the study of the relation between the stimulus (physics) and perception (psycho).

• They conceive sensation as a mental fact.
• They created experimental procedures so to analyze perceptions based on sensations.
• They focused on thresholds

Psychophysics: Perceptual Responses to Stimuli

Psychophysics from weber and fechner to the present: There are a number of perceptual responses to a stimulus:

1. Describing.
2. Recognizing.
3. Detecting absolute threshold.
4. Detecting differential threshold.
5. Perceiving magnitude.
6. Searching.
7. Other responses and methods.

Psychophysics 1: Descriptive Phenomenology

Psychophysics 1. (descriptive phenomenology) When a researcher asks a person to describe what he or she is perceiving or to indicate when a particular perception occurs.this is where the study of perception begins. Can be as simple as:

• Notice that we can perceive some objects as being far away from others
• Noticing that there is a perceptual quality in things (color) Noticing the different qualities of taste: bitter, sweet and sour

Psychophysics 2: Recognition

Psychophysics 2 (recognition) When we categorize a stimulus by naming it, we are measuring recognition Determining a person's ability to recognize objects provides information about what a person is perceiving. The procedure for measuring recognition is simple:

• A stimulus is presented and the observer indicates what it is. This procedure is used in testing patients with brain damage. Often the stimuli are pictures of objects rather than the actual object

Psychophysics 3: Detecting Absolute Threshold

Psychophysics 3 (detecting absolut theory) The absolute threshold is the smallest amount of stimulus energy necessary to detect a stimulus Examples of absolute threshold for diff sensory modalities

• Vision: A candle flame 40 km away.