Cognitive Psychology Notes PDF

March 11, 2025 1235 AM [2 ] Mind memory (he was able to call to mind what he was doing on the day of the accident) problem-solver (ˮIf you put your mind to it, I'm sure you can solve that math problem.ˮ) decision (ˮI haven't made up my mind yetˮ) normal/abnormal f...

March 11, 2025 1235 AM [2 ] Mind memory (he was able to call to mind what he was doing on the day of the accident) problem-solver (ˮIf you put your mind to it, I'm sure you can solve that math problem.ˮ) decision (ˮI haven't made up my mind yetˮ) normal/abnormal functioning (“He is of sound mind and bodyˮ or “When he talks about his encounter with aliens, it sounds like he is out of his mind.ˮ) intelligence (“He has a brilliant mind.ˮ ) Evolution structuralism ( ) experience > combining basic elements of elements: sensations + = > + ___ = analytic introspection : participants trained to describe experience and thought processes in response to stimuli problems: mental process occurs outside conscious awareness ex) reward distortion ( even though we know what we are doing we need to interpret > can have distortion in many way (into language) time gap and actual experience and time report ( cannot guarantee that it can be same) 1 ex) Difficulty in objective verification there's no reliable way of the accuraticy of the report. (ex: 2 mans have the same stimuli > different report) measuring mental process  Donder's study of reaction time (how long does it take a person to make a decision? measures interval between stimulus presentation and person's response to stimulus choice RT Simple RT  time to make a decision 0.1 sec to make decision mental reprocess cannot be measured directly but can be inferred from the P observing behavior  Ebbinghaus's memory experiment (what is the time course of forgetting? savings= (original time to learn list)- (time to relearn list after delay) 1000400600  learning and relearning after 3 different delays, shows that longer delays result in smaller savings savings curve savings> drops rapidly in 2days and then levels off we can us mathematic to describe a property in mind person procedure results and conclusions contribution Choice reaction time takes Simple reaction time First cognitive 1/10 seconds longer; Donders versus choice psychology therefore, it takes 1/10 second reaction time experiment to make a decision Forgetting occurs rapidly in Quantitative Savings method to Ebbinghaus the first 1 to 2 days after measurement of measure forgetting original learning mental processes 2 Behaviorisim  Watson (observable behavior is the only) only focus on what we can observe > bahavior not consciousness (thinking, emotions, reasoning) behavior: only focus in what happens(stimulus) can response(behavior) (no roomful cognition rejects introspection as a method, and eliminate the unobserved mental events. “little Albertˮ experiment : demonstrated that behavior can be analyzed without any referent to the mind  Pavlov Classical conditioning - paring one stimulus with another> changes in response to the previously neutral (condition) stimulus ex) Pavlov's pairing of food made the dog salivate  Skinner operant conditioning - shape behavior > rewards/punishments more likely to be repeated> - punished behavior less likely tone repeated a controversy over language acquisition Skinner - verbal behavior − children learn language through operant conditioning ex) children imiating speech they hear correct speech is rewarded  Chomsky 3  argued that children do not only learn language through imitation and reinforcement ex) “I hate you momˮ ,ˮ the boy hitted the ballˮ Information - processing approach MInd ex) Cherry's attention experiment “inputˮ > sounds of both the attended and unattended messages “filterˮ > the attended message and filters out the unattended message “detectorˮ > records the information that gets through the filter Atkinson and Shiffrinʼs 1968 model of memory Endel Tulving 1972 divided long- term memory into three components. 4 [3 ] Cognitive Neuroscience To know how the mind works> we need to Analyze behavioral experiments+physiological experiments Level of analysis - different POV - “viewpointˮ whole brain - specific structures - neurons- chemical processes Neurons: communication& processing receive and transmit information Nerve net (early concept) -its like a highway network > they can go anywhere streets are connected without stop signs nonstop, continuous communication of signals throughout the network Ramon Cajai individual nerve cells transmit signals and are not continously linked with other cells ( independent) Cajalʼs Discovery (Summary) Golgi Stain Method Stains less than 1% of neurons, making individual neurons visible. 5  Helps distinguish neurons from dense brain tissue. Key Findings Studied newborn brain tissue (lower cell density = clearer view). Discovered that the nervous system is not a continuous network. Instead, it is made up of individual units called neurons. Neuron Doctrine Neurons are separate cells that transmit signals. They are not directly connected but communicate through junctions. Later, these connections were identified as synapses. neurons: create, receive, and transmit information in the nervous system cell body: contains mechanisms to keep cell alive Dendrites: multiple branches> receive information from other neurons axon: transmits electrical signal to other neurons How Neurons Talk! Measuring Neuron Activity Microelectrodes  Tiny tools that listen to neuron signals! Recording Electrode  Goes inside the neuron (to check inside electricity ) Reference Electrode  Stays outside the neuron (to compare ) What Happens?  Measures the electric difference between inside & outside! Action Potential (Nerve Impulse) What is it?  A tiny electric signal that carries messages! 6  How long?  Super fast! Only 1 millisecond (msec) Where does it go? Starts in the axon of a neuron Travels down the axon like a rollercoaster Reaches the next neuronʼs dendrites → "Hey buddy, hereʼs the message!" Action Potentials All-or-None Rule Size never changes  Always the same strength! It either happens 100% or doesnʼt 0%  Like a light switch! What Changes? (Firing Rate) Weak stimulus → Slow firing Few action potentials) Strong stimulus → Fast firing Many action potentials) Why Is This Important? Helps us feel the difference between soft touch & hard hit! More action potentials = stronger sensation (louder, brighter, more pain! Synapse Synapse  There is a small gap between neurons where signals are passed. Not directly connected! -between neurons -release chemical neurotransmitters -neurotransmitters affects how the neurons response -when the signal arrives -allow the neurons to communicate 7 Feature Detectors & Neuron Communication How Nerve Impulses Represent Qualities: How do neurons represent different qualities (like shape, color, or movement)? The answer: Some neurons respond specifically to certain features of a stimulus (e.g., orientation, movement, etc.). Hubel & Wieselʼs Experiment (1960s): Method: Presented visual stimuli to cats and recorded which neurons fired in response. Findings: Neurons in the visual cortex responded to specific features (like orientation, movement, length). These neurons were called "feature detectors" because they detect specific features of a stimulus. Feature Detectors and Perception: Link to Perception: Our perception is shaped by neurons firing to specific features (e.g., vertical vs. horizontal lines). Feature detectors are crucial for recognizing different visual qualities in the world. Experience-Dependent Plasticity (Blakemore & Cooper, 1970): Method: Kittens were raised in an environment with only vertical stripes (no horizontals). Results: Kittens only reacted to verticals and ignored horizontals. Their visual cortex adapted to respond mainly to vertical stimuli and not to horizontal stimuli. Kittens raised with only horizontal stripes had neurons that responded mainly to horizontals. Conclusion: The brainʼs structure is shaped by experiences (experience-dependent plasticity), influencing what we perceive. Neurons Responding to Specific Features (Tree Example): 8  Neurons in the visual system fire to specific features of a stimulus. For example, when we look at a tree, different neurons respond to: The vertically oriented trunk Branches at various orientations Complex combinations of features The representation of the tree in the brain is created by the combined response of many feature detectors. Charles Gross's Experiment: The experiment recorded individual neurons in the monkey's temporal lobe. A variety of visual stimuli (lines, squares, circles, etc.) were presented to anesthetized monkeys. Initially, the neurons did not respond to the basic stimuli. However, when the experimenter cast a hand shadow on the screen, one neuron fired significantly. This neuron responded best to a hand-like shape, especially with fingers pointing up. Other Stimuli: Later research discovered neurons that specifically responded to faces. Neurons that respond to faces do not respond to other stimuli. Hierarchical Processing: Neurons in the visual cortex respond to simple stimuli, and their signals are passed to higher areas of the visual system. Neurons at higher levels respond to more complex stimuli, such as geometrical objects. At even higher levels, neurons respond to more complex stimuli like faces. This process, where information moves from simpler to more complex representations, is called hierarchical processing. Hierarchical means “arranged in layers.ˮ So, hierarchical processing is like information moving through a series of layers in the brain: Layer 1 Basic features like lines and edges. Layer 2 Combining those features into shapes. 9  Layer 3 Recognizing complex objects like faces or animals. Sensory coding 1. Specificity Coding This theory suggests that a single neuron (or a very small set of neurons) is responsible for detecting and representing a specific stimulus. Example: If there were a "grandmother cell," it would fire only when you see your grandmother and not for anything else. Problem: This is unlikely because if that neuron dies, you would lose the ability to recognize that stimulus. 2. Population Coding This theory states that a large group of neurons work together to represent a single stimulus. Instead of relying on just one neuron, the brain interprets information by analyzing the pattern of activity across many neurons. Example: When recognizing a face, multiple neurons fire in a unique pattern to encode its identity. Advantage: More flexible and resistant to damage—losing one neuron does not erase recognition. 3. Sparse Coding This is a middle ground between specificity and population coding. It suggests that only a small number of neurons fire for a given stimulus, but each neuron can respond to multiple stimuli. Example: A particular neuron might respond to both your grandmother and your best friend, but in different patterns combined with other neurons. Advantage: It is more efficient than population coding because it uses fewer neurons while still being robust to damage. 10 Localized representation -localization of function specific functions are sereved by specific brain areas Neuropsychology the study of the behavior of people with brain damage Double dissociation occurs when:  Damage to Brain Area X → Function A is impaired, but Function B is intact.  Damage to Brain Area Y → Function B is impaired, but Function A is intact. This proves that Function A and Function B are controlled by separate, independent brain mechanisms. Example: Face Recognition vs. Object Recognition Patient 1 Prosopagnosia  Face Blindness) Cannot recognize faces (Function A is impaired). Can recognize objects (Function B is intact). Damage: Fusiform Face Area FFA in the temporal lobe. Patient 2 Visual Object Agnosia) Cannot recognize objects (Function B is impaired). Can recognize faces (Function A is intact). Damage: Different part of the temporal lobe. 11 Broca's area language production (damage) frontal lobe Broca's aphasia Speech is slow, labored, and grammatically incorrect. Understanding of language is intact, but speaking is difficult. peech is fragmented, hesitant, and unstructured (e.g., “Uh... stroke and un... hot tub and... hospital and uh... ambulanceˮ). Wernicke's area language comprehension Temporal lobe wernicke's aphasia -fluent and grammatically correct -not coherent Patient speaks fluently but produces meaningless sentences: “It just suddenly had a feffort and all the feffort had gone with it. It even stepped my horn. They took them from earth you know.ˮ Speech sounds normal in rhythm and structure but lacks meaning. Fluent speech but lacks meaning ("word salad"). Difficulty understanding spoken and written language. Inability to match words with their meanings. Feature Brocaʼs Aphasia Wernickeʼs Aphasia Location Left frontal lobe Broca's area) Left temporal lobe Wernickeʼs area) Speech Production Slow, labored, ungrammatical Fluent but nonsensical 12  Speech Comprehension Mostly intact Severely impaired Localization Demonstrated by Brain Imaging Fmri) Functional magnetic resonance imaging (fmri) fMRI Mechanism: Measures brain activity by detecting oxygenated hemoglobin, which increases its magnetic properties in response to neural activity. Experiment Setup: The personʼs head is placed in an fMRI scanner while they perform cognitive tasks. Voxel Analysis: Brain activity is recorded in small cube-shaped units (voxels), similar to pixels but in 3D. Color Representation: Activation patterns are shown in colors, indicating increases or decreases in activity. Statistical Processing: Colored areas do not appear instantly; they are calculated by comparing brain activity during rest and task performance. Fusiform Face Area FFA Located in the fusiform gyrus (temporal lobe), responsible for face perception. Damage to this area causes prosopagnosia Kanwisher et al., 1997. Parahippocampal Place Area PPA Activated when viewing indoor and outdoor scenes, processing spatial layout information Aguirre et al., 1998; Epstein et al., 13  1999. Extrastriate Body Area EBA Responds to images of bodies and body parts, but not faces Downing et al., 2001. Movie Scenes and Category Labeling) Participants watched movie clips while inside an fMRI scanner. Researchers categorized objects and actions in each scene into 1,705 categories. Examples: A desert scene → labeled with butte, desert, sky, etc. A conversation scene → labeled with woman, talk, gesticulate, etc. These labels were used to analyze which areas of the brain responded to specific categories. Figure 2.20 Brain Activation for Specific Stimuli) Different brain regions respond to different types of stimuli (e.g., faces, buildings, animals). Examples: “Humansˮ region  Corresponds to the Fusiform Face Area FFA, which processes faces. “Talkingˮ region  Linked to Brocaʼs area & Wernickeʼs area, responsible for speech. “Buildingsˮ region  Activates when viewing structures or indoor scenes. 14 Key Findings of the Study  Specific brain areas are responsible for processing different stimuli. The FFA processes faces, Brocaʼs and Wernickeʼs areas process speech, The EBA processes bodies and body parts.   However, brain activity is not isolated to single regions—it is distributed. Even when looking at a face, multiple brain areas work together. This means cognition is supported by both localized functions and distributed processing. distributed representation Looking at a face triggers responses to different aspects of the face. In addition to recognizing an object as a face, we also respond to: Emotional aspects (“She is smiling, so she is probably happy,ˮ “Looking at his face makes me happy.ˮ) Direction of gaze (“Sheʼs looking at me.ˮ) Facial movements (“I can understand him better by watching his lips move.ˮ) Attractiveness (“He has a handsome face.ˮ) Familiarity (“I remember her from somewhere.ˮ) This multidimensional response to faces is reflected in distributed neural responses throughout the cortex. The activation of multiple brain areas when looking at a face is called distributed representation. Cognitions, including perception, memory, and thinking, activate numerous and sometimes widely separated brain areas. 15 memory Memories are complex and activate different brain areas. Short-term memory lasts 1015 seconds unless repeated. Long-term memory lasts from days to years. Types of Long-Term Memory Episodic Memory  Personal experiences (e.g., what you did yesterday). Semantic Memory  Facts and knowledge (e.g., the capital of California). They activate different brain areas Figure 2.22. Memory in the Brain Memory involves multiple brain regions. Types of memory cues: Visual (picturing a place) Auditory (remembering a song) Olfactory (smell triggering a memory) Emotional (thinking of someone you miss) Memories create a symphony of neural activity. language processing processing sound, producing speech, saying words understanding words 16 Neural networks Neural networks in the brain are like a vast system of roads and highways that allow different areas to communicate with each other. Researchers have discovered four key ideas about how these networks work:  Structural Pathways: Think of these as highways in the brain that physically connect different regions. These pathways help information travel from one area to another.  Functional Pathways: Within those highways, there are different "routes" that serve specific purposes—some pathways help with vision, others with memory, language, or movement.  Dynamic Operation: The brain is always changing and adapting, just like a city with traffic patterns that shift throughout the day. Different networks become active depending on what youʼre thinking or doing.  Resting State Activity: Even when you're not thinking about anything specific, parts of your brain are still active—like streetlights and security cameras that stay on even when thereʼs no traffic. connectome “structural description of the network of elements and connec- tions forming the human brainˮ chapter summary 1. Cognitive neuroscience is the study of the physiological basis of cognition. Taking a levels-of-analysis approach to the study of the mind involves research at both behavioral and physiological levels. 2. Ramon y Cajalʼs research resulted in the abandonment of the neural net theory in favor 17 of the neuron doctrine, which states that individual cells called neurons transmit signals in the nervous system. 3. Signals can be recorded from neurons using microelectrodes. Edgar Adrian, who recorded the first signals from single neurons, determined that action potentials remain the same size as they travel down an axon and that increasing stimulus intensity increases the rate of nerve firing. 4. The principle of neural representation states that everything that a person experiences is based not on direct contact with stimuli, but on representations in the personʼs nervous system. 5. Representation by neurons can be explained by considering feature detectors, neurons that respond to complex stimuli, and how neurons are involved in specificity coding, population coding, and sparse coding. 6. The idea of localization of function in perception is supported by the existence of a separate primary receiving area for each sense, by the effects of brain damage on perception (for example, prosopagnosia), by recording from single neurons, and from the results of brain-imaging experiments. 7. Brain imaging measures brain activation by measuring blood flow in the brain. Functional magnetic resonance imaging (fMRI is widely used to determine brain activation during cognitive functioning. Brain-imaging experiments have measured the response to still pictures to identify areas in the human brain that respond best to faces, places, and bodies, and the response to movies to create a brain map indicating the kinds of stimuli that activate different areas of the brain. [4 ] Perception the experience that result from stimulation of the senses environmental energy -recieved by sensory receptors -converted into electrical energy -interpreted by brain 18 + allows us to recognize what exists in our environment serves as a gateaway to other cognitive abilities influenced by context emotional state past experiences why is it hard to design a perceiving machine? the stimulus on the receptors is ambiguous -an image on the retina can be cause by an infinite number or objects Many different objects (e.g. tilted shapes, larger pages) can create the same retinal image. -inverse projector problem starts with that image and tries to guess what object caused it. determining the object responsible for a particular image on the retina Objects Can Be Hidden or Blurred Some objects are partially hidden (occluded) or blurry, but people can still recognize them. Example: You can still find a pencil or glasses in an image, even if only a small part is visible. 19 The brain fills in the gaps, assuming the hidden part still exists. This skill helps us understand complex scenes, where many objects overlap. Even blurry objects like faces out of focus can still be recognized by people. Computers struggle with both occluded and blurry object recognition. -the interpretation or hidden objects are ambiguous objects can be blurred -people easily recognize objects not in sharp focus objects look different from different viewpoints -the ability to recognize an object regardless of the viewpoint information for human perception What is Perception? Perception is how we understand and make sense of what we see, hear, and feel around us. Itʼs like your brain interpreting what your senses (eyes, ears, etc.) pick up. -the human perceptual system uses two types of information Bottom-Up Processing This is how perception starts:  You look at something.  Light from the object hits your retina (in your eye), creating an image.  This image gets turned into electrical signals.  Those signals travel to your brain, where theyʼre processed. 20 it begins with raw information coming from the environment and moves up to the brain. Top-Down Processing But perception doesnʼt stop there! Your brain adds extra info: It uses your knowledge (what youʼve learned before), Your past experiences, And your expectations (what you expect to see in a situation). This is called top-down processing because it starts from the top (your brain) and helps interpret what youʼre seeing. Example: Imagine you're in a kitchen, and you see something blurry on the counter. If it looks kind of like a spoon, your brain says: "Hey, spoons are common in kitchens, so thatʼs probably a spoon!" Thatʼs top-down processing helping you identify it quickly based on the scene and your past knowledge. type how it works example bottom-up info goes from eyes/ears > brain Seeing a shape on a page processing Brain uses knowledge to interpret Recognizing a blurry spoon in a top-down processing things kitchen -top down processing speech segmentation the ability to tell when one word ends and another begins 21  Hearing Words in a Sentence Speech sounds are continuous—there are no clear breaks between words. Speech segmentation  The brain's ability to separate sounds into individual words. If you understand the language, your brain uses top-down processing to hear separate words. If you donʼt understand the language, it sounds like one long stream of noise (just bottom-up input). the Gestalt approach to perceptual grouping how do we perceive objects? -grouping of elements into a single objects is important Gestalt psychology rejected the idea of “adding upˮ sensation to form perception -perception is not built up from sensations but is a result of perceptual organization even though nothing is actually moving, our brain thinks it sees movement. This illusion is called apparent movement. Here's how the illusion works: There are three steps involved:  First light flashes on and off Imagine a small light on the left side blinks quickly.  Short period of darkness Everything goes dark for a split second.  Second light flashes on and off Then, a small light on the right side blinks. 22 Physically, thatʼs just two lights turning on and off one after the other, with darkness in between. But what do we see? Our brain fills in the gap. We donʼt see the darkness in between. Instead, we see a single light moving from left to right—even though no light is actually traveling between the two spots. Electronic signs Like scrolling news headlines on LED boards. Movies Made of still images shown very fast one after the other. Yet we see people walking, running, and talking smoothly. Principle of Good Continuation Definition We see elements as connected when they form a smooth line or curve. Overlapping objects We assume hidden parts continue behind other objects. Example 1 Coiled rope Crystal sees overlapping rope loops and assumes it's one piece. When she lifts it, it's not surprising—it looks continuous. Example 2 Shoelaces Even though parts are hidden under loops or shoes, we still see them as one lace. Key idea The brain prefers the smoothest and simplest path and fills in missing parts. pragnanz every stimulus is seen as simply as possible efinition We perceive complex images in the simplest and most organized way possible. We see the Olympic logo as five clean, overlapping circles. We donʼt see it as a bunch of broken or complex shapes (like in the “explodedˮ version). This shows how the brain simplifies the pattern into something familiar and easy. 23  Relation to Good Continuation We follow the smooth, curved lines of the circles. Even when parts are hidden or overlap, we still perceive whole circles. Good continuation helps support the simple interpretation. Principle of Similarity (A Gestalt Principle) Definition: We tend to group things together when they look similar—in color, shape, size, or orientation. Gestalt Psychologistsʼ Bigger Idea They believed perception isnʼt just about the light hitting your eyes (retina). Instead, your brain organizes that information using built-in rules (like similarity, continuation, etc.). principle definition example perceive patterns in the simplest The Olympic rings are seen as five full Pragnanz way possible circles, not as complex broken shapes. Circles with the same color appear as group things that look alike (color, similarity columns or rows, even if spaced the shape, size, etc.). same. group things that are close Objects that are near each other are Proximity together in space. seen as belonging to the same group. group things that move together in A group of birds flying together looks Common Fate the same direction or speed. like one flock, not separate birds. Shapes inside the same box or Elements within the same enclosed Common region bordered space are grouped, even if far area are seen as belonging together. apart or different. Elements that are visually Dots connected by a line or bar are Uniform connected (e.g., by lines or seen as a unit, even if they donʼt look connectedness shading) are grouped. similar. gestalt approach -perception is determined by specific organizing principles, not just dark and light stimuli activating the retina. 24 -role of experience is minor compared to these intrinsic.'built n'principles. -experience can influence perception but is not the only key driver regularities in the environment -experience with the characteristics of environment influences perception -physical regularities (vertical&horizontals are common) The Oblique Effect People perceive vertical and horizontal lines more easily than other orientations Light-From-Above Assumption We assume light comes from above, influencing how we see shapes/shadows Semantic Regularities The meaning of a scene and what usually happens there Regularities in Perception Concept Meaning Example Physical Frequently occurring visual More vertical and horizontal lines (like walls, Regularities features in the environment trees) than slanted ones people perceive verticals and We detect a straight pole faster than Obilique effect horizontals more easily than a diagonal stick angled lines 25  We assume light comes from Light-from-above A dent in the sand looks like a bump when above, influencing how we see assumption the image is flipped shapes/shadows Expectations about what Semantic In a kitchen → expect food, cooking, utensils; happens in certain types of regulatities in an airport → luggage, security etc. scenes the interaction of perception and action -constant coordination occurs in the brain as we perceive stimuli while also taking action toward them. Ablation the destruction or removal of tissue in the nervous system Underleider and Mishkin -object discrimination problem -a reward is given for detecting the target object Landmark discrimination problem pathway function brain area also called “whatˮ pathaway identifying what something is Temporal lobe (bottom) Ventral pathaway “whereˮ pathaway locating where something is Parietal Lobe (top) Dorsal pathaway 26 damaged problem preserved ability key task conclusion pathway observed Poor at - Matching Shows that ventral matching Could perform task orientation stream is Ventral (what) object when it task (fail) - for perception (what), pathway orientation involved action like "Mailing" card and dorsal helps when just mailing a card task (success) with action (how/where) looking  Could Poor at visually describe or Shows that dorsal Unimpaired object Dorsal guided action identify shape stream is crucial recognition – Where/How) (grabbing (success) - for action, even if could identify Pathway objects Couldnʼt reach object recognition is objects easily properly) accurately for fine object (fail) Color constancy Explains how our brain keeps color perception stable despite changes in lighting. Brightness Similar idea, but with light and dark — brain adjusts to maintain perception of constancy brightness. Shows perceptual ambiguity — the same image can lead to two different Necker cube perceptions. Illustrates depth perception tricks — brain uses context to judge size and Ponzo illusion distance. An illusion that messes with perceived size and space, showing that perception Ames room can be easily fooled. 27 1. The example of Crystal running on the beach and having coffee later illustrates how perception can change based on new information, how perception can be based on principles that are related to past experiences, how perception is a process, and how perception and action are connected. 2. We can easily describe the relation between parts of a city scene, but it is often challenging to indicate the reasoning that led to the description. This illustrates the need to go beyond the pattern of light and dark in a scene to describe the process of perception.  1. The example of Crystal running on the beach and having coffee later illustrates how perception can change based on new information, how perception can be based on principles that are related to past experiences, how perception is a process, and how perception and action are connected.  2. We can easily describe the relation between parts of a city scene, but it is often challenging to indicate the reasoning that led to the description. This illustrates the need to go beyond the pattern of light and dark in a scene to describe the process of perception. 3. Attempts to program computers to recognize objects have shown how difficult it is to program computers to perceive at a level comparable to humans. A few of the difficulties facing computers are 1 the stimulus on the receptors is ambiguous, as demonstrated by the inverse projection problem; 2 objects in a scene can be hidden or blurred; 3 objects look different from different viewpoints; and 4 scenes contain high-level information. 4. Perception starts with bottom-up processing, which involves stimulation of the receptors, creating electrical signals that reach the visual receiving area of the brain. Perception also involves top-down processing, which is associated with knowledge stored in the brain.  Examples of top-down processing are the multiple personalities of a blob and how knowledge of a language makes it possible to perceive individual words. Saffranʼs experiment has shown that 8-month-old infants are sensitive to transitional probabilities in language. 28   The idea that perception depends on knowledge was proposed by Helmholtzʼs theory of unconscious inference.  The Gestalt approach to perception proposed a number of laws of perceptual organization, which were based on how stimuli usually occur in the environment.  Regularities of the environment are characteristics of the environment that occur frequently. We take both physical regularities and semantic regularities into account when perceiving.  Bayesian inference is a mathematical procedure for determining what is likely to be “out thereˮ; it takes into account a personʼs prior beliefs about a perceptual outcome and the likelihood of that outcome based on additional evidence.  Of the four approaches to object perception—unconscious inference, Gestalt, regularities, and Bayesian—the Gestalt approach relies more on bottom-up processing than the others. Modern psychologists have suggested a connection between the Gestalt principles and past experience.  One of the basic operating principles of the brain is that it contains some neurons that respond best to things that occur regularly in the environment.  Perceiving and taking action are linked. Movement of an observer relative to an object provides information about the object. Also, there is a constant coordination between perceiving an object (such as a cup) and taking action toward the object (such as picking up the cup).  Research involving brain ablation in monkeys and neuropsychological studies of the behavior of people with brain damage have revealed two processing pathways in the cortex—a pathway from the occipital lobe to the temporal lobe responsible for perceiving objects, and a pathway from the occipital lobe to the parietal lobe responsible for controlling actions toward objects. These pathways work together to coordinate perception and action.  Mirror neurons are neurons that fire both when a monkey or person takes an action, like picking up a piece of food, and when they observe the same action being carried out by someone else. It has been proposed that one function of 29  mirror neurons is to provide information about the goals or intentions behind other peopleʼs actions.  Prediction, which is closely related to knowledge and inference, is a mechanism that is involved in perception, attention, understanding language, making predictions about future events, and thinking. [5 ] Attention the process which results in certain sensory information being selectively processed over other information "Your brain picks and chooses what to focus on." Attention Definition Rogerʼs Example Selective Focusing on one thing while Trying to focus on math homework while Attention ignoring others ignoring people talking One stimulus interfering with the Conversation interfering with his cell phone Distraction processing of another game Paying attention to more than Listening to the conversation while playing Divided Attention one thing at the same time the game Attentional A sudden shift of attention Loud noise from overturned book cart pulling Capture caused by a strong stimulus his attention away Moving the eyes from one Looking from one face to another to identify Visual Scanning object/location to another the people across the room Dichotic listening where two different audio messages are played into each ear. People were told to pay attention to only one ear (the attended ear) and repeat what they heard out loud. This repeating is called shadowing. Cherry found: People could repeat the message from the attended ear well. They noticed the voice (male or female) in the unattended ear, but... 30  Lavieʼs Load Theory of Attention – Summary  Your brain has limited processing capacity (like a cup — it can only hold so much ).  Low-load tasks (easy stuff): Use less brainpower Leave extra space in your attention ➤ You get more easily distracted by irrelevant things (like a cartoon character)  High-load tasks (hard stuff): Use all your brainpower No space left for distractions ➤ You stay focused, even if other stuff is happening around you  BUT — super powerful distractions (like a fire alarm or the Stroop effect) can still grab your attention, even during hard tasks. stroop effect( name of the word interferes with the ability to name the ink color over attention -shifting attention from one place to another by moving eyes Scanning Based on Cognitive Factors = Top-Down Attention This is when your thoughts, goals, knowledge, or past experiences guide where you look in a scene—not just what pops visually. scanning a scene with eye movements fixations: pauses in eye movements that indicate where a person is attending When your eyes stop briefly to look at something saccades: small, rapid eye movements When your eyes jump quickly from one point to another approximately 3 fixations per second scanning based on stimulus salience 34  areas of stimuli that attract attention due to their properties What Grabs Your Attention? Stimulus Salience is all about how certain physical features of things—like color, contrast, or motion—stand out and naturally grab your attention. So, if somethingʼs bright red, super shiny, or moving fast, your eyes will automatically snap to it. This is a bottom-up process—meaning itʼs driven by the stimulus itself, not by what youʼre thinking or expecting. Youʼre not choosing where to look… your brainʼs just reacting to what pops. attention capture stimulus salience causes an involuntary shift of attention saliency map determined by analyzing the color, contrast, orientations in the scene. bottom-up process that is unrelated to meaning scene schema prior knowledge about what is found in typical scenes fixations are influenced by this knowledge observers spent more time looking at an unexpected object. task demands determine where people look as they carry out tasks. 35  the timing of when people look at specific places is determined by the sequence of actions involved in the task Key points: Eye movements follow the sequence of actions — you look where you're about to act. You use a “just in timeˮ strategy — your eyes grab info right before you need it. You donʼt waste time looking at irrelevant stuff — only what helps you complete the task. This shows predictive scanning — your eyes anticipate whatʼs next, based on experience and expectations. covert attention -occurs when you shift attention without moving your eyes. -refers to attention without looking Imagine: You're staring at the teacher but you're secretly watching your crush out the corner of your eye... yeah, thatʼs covert attention It shows how attention works in your mind, without eye movement interfering. It helps us see how fast and accurately we react to stuff just by mentally shifting focus. It tells us how we notice, respond to, and even perceive things without physically looking at them. outcomes of attention attention improves responding to a location spatial attention: attention to specific locations Summary: Posnerʼs Precueing Experiment Goal To find out if focusing attention on a location (without moving your eyes) helps you respond faster when something appears there. Method Participants looked at a fixed point and saw an arrow (cue) telling them where to focus their attention. Valid trials The target appeared where the arrow pointed. Invalid trials The target appeared on the opposite side. 36 Result Participants responded faster in valid trials. Conclusion Attention improves processing at the location itʼs directed to—even without eye movement. It acts like a spotlight, enhancing what it focuses on. Summary: Egly et al. (1994) – Same-Object Advantage Goal To see if attention spreads across an entire object, not just a single location. Method: Participants looked at a + sign. A cue highlighted one end of a rectangle. Then a target appeared at one of three spots: A: same spot as the cue B: other end of the same rectangle C: same distance, but on a different rectangle Task: press a button when the target appeared. Result: Fastest at A (where attention was focused). Faster at B than C, even though they were equally far from A. Conclusion: Attention spreads across the whole object. This is called the same-object advantage. Summary: Datta & DeYoe (2009) – Attention Maps in the Brain 37  Goal To see how shifting attention (without moving eyes) affects brain activity. Method: Participants stared at the center of a screen. fMRI measured brain activity as they shifted attention to different spots. Result: Different areas of the brain lit up depending on where attention was focused. These areas created “attention mapsˮ showing which brain spots match which visual locations. Bonus: When participants focused on a secret location, researchers used the brainʼs hot spot to guess the spot—with 100% accuracy. Conclusion: Directing attention to a specific place in space activates specific areas in the brain—even if your eyes donʼt move. physiology of attention attention to objects increases brain activity in specific areas that process corresponding object category attention and experiencing a coherent world binding 38 the process by which features such as color,form,motion, and location are combined to create our perception of coherent object binding problem hoe an objectʼs individual features become together? Feature Integration Theory & Illusory Conjunctions Treisman & Schmidt 1982 showed that when our attention is divided, we can mix up features from different objects—this is called an illusory conjunction. Example: See a red triangle and a green circle but report a red circle and green triangle Why? ➤ In the preattentive stage, features like color and shape are "free-floating" and not yet connected to an object. ➤ Without focused attention, the brain miscombines them. Real-life example A student saw a man in a green shirt steal a yellow purse… but reported a man in a yellow shirt with a green purse. Classic mix-up preattentive stage features of objects are separated focused attention stage features are bound into a coherent perception 39 feature integration theory 1. Feature Search (Easy Mode ) Youʼre just looking for one feature. Example: "Find the horizontal line." You can spot it fast—your brain doesnʼt need to focus hard. It pops out right away. No attention-at-a-location needed. 2. Conjunction Search (Hard Mode ) Youʼre searching for a combination of features. Example: "Find the green horizontal line." Now you canʼt just look for green or horizontal—you have to scan and focus your attention on each object to find both features in one spot. Inattentional Blindness  When you donʼt notice something right in front of you because your attention is focused elsewhere. Examples:  Cross & Square Experiment: People focused on telling which line of a cross was longer. A small square appeared nearby, but most didnʼt see it.  Gorilla Video: People counted basketball passes. A gorilla or umbrella woman walked by. Almost half didnʼt notice it at all. 3.change blindness Why does it happen? 40 Because our attention isnʼt focused on the right spot when the change occurs. We only notice what weʼre paying attention to, not everything on screen. ex) distraction by cell phones while drving -anything that distracts attention can degrade driving performance -gps,talking to passengers 41