2210 Psych Midterm 1 Study Guide PDF

Unit 1: Introduction & Anthropomorphism ======================================= Chapter 1 -- History of Comparative Cognition Major Historical Figures ------------------------ **René Descartes (1596-1650)** - **"Cartesian Dualism"** - Two classes of human behaviour -- voluntary and invo...

Unit 1: Introduction & Anthropomorphism ======================================= Chapter 1 -- History of Comparative Cognition Major Historical Figures ------------------------ **René Descartes (1596-1650)** - **"Cartesian Dualism"** - Two classes of human behaviour -- voluntary and involuntary - Involuntary -- reflexes triggered by external stimuli - Voluntary -- product of conscious intent - Involuntary behaviour was the only one available to non-human animals -- so all behaviour in non-human animals was reflexive - Free will and voluntary behaviour considered uniquely human traits (humans have a mind and/or soul) - Mind is non-physical entity, connected to brain via the pineal gland, which allows for voluntary behaviour independent of external stimulation - **Nativism** - Mind contained ideas that were innate and existed in all human beings independent of personal experiences - Ideas included the concept of God, the concept of self, and basic geometric principles **John Locke (1632-1704)** - **Empiricism** - People are born with no preconceptions about the world -- born with a clean slate or *"tabula rasa"* - Idea that we acquire our ideas and information as we experience the world is referred to as empiricism **Hermann Ebbinghaus (1850-1909)** - **Rules of Association** - How associations are formed using nonsense syllables - Used himself as a subject - Ebbinghaus studied lists of nonsense syllables (ex: PZD, KOJ) under various experimental conditions, then tested his ability to recall them. - Allowed him to determine if the strength of association increased with training, if items close together are associated more closely than those far apart, backwards and forwards associations **Charles Darwin (1809-1882)** - **Darwin's Theory of Evolution** - **Tenets of Natural Selection:** - Variation -- individuals within a species display differences in both physiological *and* behavioural traits - Heritability -- offspring inherit traits from their parents - Survival and reproduction -- individuals with traits that best promote survival have best chance of transmitting traits to offspring - A premise of comparative cognition is that cognitive traits are shaped by the same selective pressures - **Adaptation** - An evolved solution to a problem of survival and reproduction - **Speciation** - When populations of a single species get separated, they adapt to their new environment - Speciation occurs when the groups diverge to the point that they can no longer interbreed - The process by which new species evolve; usually as the result of isolation from the main population - **Continuity Hypothesis** - The idea that trait differences between animals and humans will be quantitative, not qualitative - So, humans and animals may differ greatly in ability, but the difference is not in trait...rather it is how the trait is expressed - Animals possess some, if not all, cognitive and emotional traits that humans have, even if only at an incipient level - Modern comparative psychologists do not assume that animals have all human traits; rather, we test such hypotheses experimentally - Believed in not only the evolution of physical traits, but also the evolution of psychological abilities - Believed that animals, like humans, had the capacity for curiosity, imitation, attention, and memory - Collected anecdotal accounts of animal intelligence **Gustave Fechner (1801-1887)** - Formalized the scientific measurement of perception (psychophysics), which paved the way for experimental psychology (started by Wundt) Four Questions of Ethology -------------------------- **Ethology:** The scientific study of the causes and adaptive value of animal behaviour; a subtopic of zoology and biology. Tinbergen proposed that behaviour should be analyzed in terms of four scientific questions: 1. **Adaptive Value:** What is the function of behaviour? 2. **Evolution:** How did the behaviour develop across evolution and how does it compare to closely related species? 3. **Ontogeny:** How does the behaviour change across the lifespan of the organism? 4. **Immediate Causation:** What are the internal mechanisms that produce the behaviour? **\***The first two questions are [ultimate] causes of behaviour, the second two are [proximate] causes of behaviour **Ultimate Cause:** A description of a trait or behaviour in terms of its adaptive value. **Proximate Cause:** A description of a trait or behaviour in terms of its development or its mechanisms. Application of the 4 questions to a specific behaviour is often illustrated by the simple observation that a male American robin (Turdus migratorius) will start to sing in the spring. 1. The function of the behaviour is mate attraction or territorial defense 2. Singing evolved in some, but not all, birds because it provided a fitness advantage in certain environments a. One possibility is that bigger and stronger birds were capable of emitting more complex vocalization so male birds displaying this trait were more attractive to females 3. The characteristic of a male song depends on exposure to other male songs during development, particularly its own father 4. Finally, male birds begin to sing in the spring when longer periods of daylight stimulate hormone production that acts on specific brain areas responsible for vocalization Fixed Action Patterns --------------------- **Konrad Lorenz (1950) & Nikolaas Tinbergen (1951)** **Fixed Action Pattern (FAP):** Stereotyped, instinctive behaviours that occur in a rigid order and are triggered by a 'sign' stimulus in the external environment. e.g., egg rolling in graylag geese (seeing an egg-sized object near the nest, it triggers a FAP that retrieves the object by rolling it back into the nest in a specific, predictable series of actions; if an experimenter removes the object in the middle of the goose's rolling, the bird will continue to engage in rolling motions as if it were bringing a phantom egg back into the nest), regurgitation in herring gulls. **Imprinting:** A particular type of learning in which exposure to specific stimuli or events, usually at a young age, alters behavioural traits of the animal. - Innate responses are not necessarily fixed - FAPs can be modified by experience -- behaviour must therefore be understood as an interaction between learning and inherited mechanisms - Lorenz -- young birds learn characteristics of the first moving object they encounter, and follow it around Different Approaches to The Study of Animal Cognition/Behaviour --------------------------------------------------------------- **Comparative Cognition (Behaviourism + Behavioural Ecology)** Three unifying hallmarks: 1. Focus on cognition a. Acquisition, storage, and processing of mental information 2. Use of experimental methodology b. Either in lab or natural environment 3. Explanation of findings within framework of evolutionary theory **Behaviourism:** A sub-discipline of psychology, associated with John B. Watson, that adheres to the principle that behaviour (not thoughts or ideas or any other cognitive process) is the only justifiable object of study in psychology. - Comparative cognition grew out of behaviourism (from the field of psychology) and behavioural ecology (from the field of zoology) - An understanding that both proximate and ultimate causes of behaviour must be considered when understanding any behaviour or cognitive process - Behaviourism maintained that only observable and measurable behaviours should be studied in psychology - In reality -- many psychologists realized that mental processes exist, and instead practiced "methodological behaviourism" **Functional Neurology** - Uses studies of learning/behaviour in nonhuman animals to gain insight into how the nervous system works - Influenced greatly by Ivan Pavlov and his belief in nervism - Highly influential in modern neuroscience **Behavioural Neuroscience:** The study of brain-behaviour relationships in all animals. - Used to study underlying mechanisms of cognition. - Examines brain systems via lesions, electrical stimulation, pharmacology, and brain imaging **Methodological Behaviourism:** An experimental approach that involves quantifiable measures of behavioural output; involves tight control of extraneous variables that may affect behavioural measures. **Behavioural Ecology:** An offshoot field of ethology that is characterized by increased attention to the ultimate causes of behaviour; the scientific study in interactions between organisms and their environment, and how these interactions result in differential survival and reproduction. - Scientific study of the evolutionary basis of animal behaviour due to the ecological pressures **Developmental Psychology:** The study of systematic changes that occur across the lifespan in humans. - Comparative cognition benefits from the fact that developmental psychology has a long and established tradition of examining changes in cognition experimentally - Non-human animals and young human infants have something in common: both non-verbal Anthropomorphism ---------------- **Anthropomorphism:** The attribution of human-like characteristics to non-human animals or objects. - Important to consider in understanding animal behaviour and cognition - Darwin -- extremely influential regarding anthropomorphism understanding - "Guilty" look in dogs (Horowitz, 2009) - Guilty look is likely a response to owner cues, rather than an acknowledgement of a misdeed - What's wrong with anthropomorphism? - Nothing - if you are not referring to it within a specific context. - From an animal welfare perspective, anthropomorphism may result in better treatment of animals. - BUT... - In a scientific context, anthropomorphism can cloud our judgement or make us too liberal in what abilities we are willing to attribute to animals. - In Conclusion...Anthropomorphism is: - The attribution of human-like qualities to non-human animals or objects. - Possibly a good (and fun!) thing in day-to-day life. - BUT... - Something we need to be extremely vigilant of in the scientific study of animal behaviour and cognition. ### Anecdotal Method **George Romanes (1848-1894)** - Initially research assistant to Darwin - Using an anecdotal method -- first to investigate systematically the comparative psychology of intelligence An Example of the "Anecdotal Method" (Romanes, 1888, p. 48): "Several ants passed it, but at least one discovered it and tried to pull it out but could not. It immediately set off at a great rate, and I thought it had deserted its comrade, but it had only gone for assistance, for in a short time about a dozen ants come hurrying up, evidently fully informed of the circumstances of the case, for they made directly for their imprisoned comrade and soon set him free." "The next that approached, as soon as it discovered its situation, ran backwards in an agitated manner, and soon communicated the intelligence to the others. They rushed to the rescue; some bit at the stone and tried to move it, others seized the prisoner by the legs and tugged with such force that I thought the legs would be pulled off, but they persevered until they got the captive free." ### Morgan's Canon **Morgan's Canon:** A term coined by the nineteenth century British psychologist C. Lloyd Morgan; the principle that animal behaviour should not be interpreted in terms of higher cognitive processes when simpler explanations are possible. **C. Lloyd Morgan** - Prompted by Romane's tendency to rely on anecdotal evidence rather than empirical tests - "In no case is an animal activity to be interpreted in terms of higher psychological processes, if it can be fairly interpreted in terms of processes which stand lower in the scale of psychological evolution and development" (Morgan, 1894, p.53) ### Clever Hans - Has was a horse owned by Wilhelm Von Osten. - Von Osten claimed that Hans could add, subtract, multiply, divide, work with fractions, tell time, keep track of the calendar, differentiate musical tones, read, spell, and understand German. - Hans was most famous for his mathematical ability...if Von Osten asked him what "4+4" was, for example, Hans would stomp his hoof 8 times in response. - "Clever Hans Cues" - Eventually, it was determined that Hans was simply responding to very subtle changes in Von Osten's posture to solve the problem. - Importantly, Von Osten was not trying to trick anybody - he genuinely believed in Hans' abilities and had no idea that he had been cueing him! - In designing behavioural experiments with animals, we are not very careful to avoid "Clever Hans Cues" Unit 2: Sensation & Perception ============================== Chapter 2 -- Sensory Systems Sensory Systems --------------- The 5 senses: 1. Hearing 2. Taste 3. Smell 4. Vision 5. Touch **Sensation:** Produced when physical stimuli in the environment activate sensory receptors, which then send neural circuits through specialized circuits. **Perception:** The interpretation of these signals which occurs when sensory information is processed, organized, and filtered within the central nervous system. - All cognitive processes are influenced, at least initially, by sensory input - This makes the understanding of sensory system evolution, development, and function across species very important - Sensory systems provide the first point of contact between an organism and its environment - Need to understand: - Evolution - Development - Function - Humans see vibrant colour in flowers, but not UV reflections which guide insects. - Humans detect odor but could not track another human or animal like a dog. - Human auditory systems are finely tuned to range of sound frequencies in speech, an advantage for verbal communication. - Visual information is also extremely important for humans, so we have evolved a complex visual system. All animals experience ***only a portion*** of the sensory world, and these generally reflect the evolutionary history of that species. - All cognitive processes are influenced at least initially by **sensory** input. - Sensory systems are the **first point of contact** between an organism and their environment. - While humans rely heavily on vision, other species have adapted to their respective environments. - Sensory information is transmitted to the central nervous system and on to different brain regions where is it processed and interpreted (ie: perception) Sensory System Adaptation ------------------------- **Evolution of sensory systems** **Visual Adaptation:** - In all animals, the visual system works by absorbing light of particular wavelengths along the electromagnetic spectrum - Humans see within 400-700nm range, because we have pigments in the eye to absorb these wavelengths - Different animals in different habitats have evolved different visual sensitivities - Evolution has also favoured traits that help animals see based on different lifestyles - Compared to diurnal animals, nocturnal animals have larger lenses that pick up more light - The tapetum lucidum (located behind the retina) also aides in the night vision of many animals, particularly nocturnal animals **Eye Placement** - Binocular vision occurs when the two visual fields overlap - The brain uses the disparity between the right and left eye to create depth perception, or stereopsis - Prey animals tend to have laterally placed eyes, resulting in less depth perception, but an extremely large field of view - Predators tend to have more forward-facing eyes, resulting in excellent depth perception, but very poor lateral vision **Binocular Vision:** Overlap of the two visual fields so that visual information reaching the two eyes is similar **Timney & Kell (1999)** - Stereopsis in horses - Horses have laterally placed eyes...do they have enough binocular overlap to detect depth perception? - Horses successfully trained to discriminate flat (+) stimulus from protruding (-) stimulus. **Sensory Adaptation in Closely Related Species** - Snakes can detect chemical, visual, and thermal cues, but they may show greater sensitivity depending on their preferred prey. - The Midland rat snake feeds on rodents and responds to ***chemical cues*** allowing them to follow odour trails. - Western fox snakes respond more to ***visual cues*** in order to hunt ground nesting birds. **Sensory Bias:** Enhanced responding to sensory stimuli that are not part of an animal's natural environment and were not part of the natural environment of their ancestors. - A paradox of the evolution of sensory systems - Occurs in situations in which individuals of a species respond with increased vigour to stimuli that are exaggerated version of naturally occurring stimuli **Sensory Exploitation:** An explanation for sensory bias; a sensory signal that has an evolutionary advantage in one context has been co-opted in another. - When sensory signals which were important for one process have been co-opted by another - Female zebra finches need white feathers to build nests - Their interest in the adorned males has nothing to do with male fitness, but rather is a "borrowed" response from their nest building behaviour **Supernormal Stimuli:** Stimuli with exaggerated naturalistic features that elicit greater responses than the natural stimuli on which they are modeled. - The principles of sensory exploitation may also explain heightened responses to exaggerated versions of natural stimuli - Tinbergen (1951): Graylag geese retrieve and attempt to incubate giant artificial eggs - Even when their actual eggs sat nearby - Stickleback fish will ignore invading conspecifics in favour of attacking wooden dummy fish with darker reed undersides ### Sensory Drive Hypothesis - Explains divergence of sensory abilities both between and within species - Facilitates communication - Developing different sensory abilities either between or within species is costly, so these capacities are lost or not developed unless needed Animals become separated by a geographical barrier (ex: mountain range) - New habitat has features that make it easier or harder to communicate in the old territory - Ex., if birds move into a territory with denser trees, lower light would make it difficult for females to detect bright plumage on males - Therefore, females with better visual acuity and males with brighter feathers, have new advantage that was not present in the old habitat **Sexual Dimorphism:** A systematic difference in a physical trait or behaviour between males and females of the same species **Sensory Drive Hypothesis:** A theory to explain ecological divergence within a species. When populations occupy new habits with different sensory environments, natural selection favours adaptations that maximize the effectiveness of intra- and inter-species communication Sensory System Development -------------------------- - Much of what is known regarding sensory system development comes from pioneering work by Hubel & Wiesel - (who won the 1981 Nobel prize for their description of how the visual system is processed and organized in the brain). - Found that when young monkey or kittens are deprived of vision for as little as 1-week, normal vision never develops. - BUT\...visual deprivation for weeks or even months in adults has no effects on vision. - Cells in the eye respond normally after deprivation, however neurons in the cortex that receive signals from these cells do not. **Sensitive Period:** The period in which experience-dependent changes can have profound and enduring effects on development. **Strabismus:** A condition in which the visual axes of the two eyes are misaligned; disrupts depth perception and binocular vision **Blakemore (1976)** - If cats are exposed to a particular visual stimulus during the first few weeks of life (horizontal versus vertical lines), their ability to detect the previously exposed pattern is enhanced in adulthood. - This shift in sensitivity occurs because connections between neurons in the visual cortex are rearranged during development, and these cortical neurons become more responsive to the familiar pattern. - Sensitive periods have been shown in cognitive processes such as ***categorization, social competence, and communication.*** **Dark Adaptation:** A reduction in the threshold for detecting light that occurs under reduced illumination. - Dark adaptation is the lowered threshold for detecting light that occurs under reduced illumination. - Takes a few minutes to develop because it involves a series of neurochemical reactions in the eye. - Evolved in some humans and animals, providing ability to see during day and night. - **Provides evidence that perceptions are not a direct reflection of sensations.** **Camouflage:** Structural adaptations that allow a species to blend in with its environment ### Compensatory Plasticity Hypothesis **Compensatory Plasticity Hypothesis:** The idea that a loss or deficit in one sense leads to a heightened capacity in another. - If sensory input (ex: vision, audition) is blocked during development, the functioning of that system may be blocked in adulthood. - Deficits in one sensory system may lead to enhanced ability in another sensory system. **Chapman et al. (2010)** - Guppies raised under different light intensities, then tested for how they responded to light or olfactory cues. - Fish raised under high light intensity respond better to visual stimuli, fish raised under low light respond better to olfactory cues. - **Compensatory Plasticity Hypothesis:** A loss or deficit in one sense results in heightened capacity in another. - Whereas natural selection is a slow process requiring many generations, compensatory plasticity allows animals to adapt, within their lifetime, to a new environment. In summary... - Most animals do not have fully functioning sensory systems at birth - Both normal development and fine tuning of sensory abilities depend on post-natal sensory experience - Nature AND nurture! ### Blindsight **Lateral Geniculate Nucleus (LGN):** A group of neurons in the thalamus that received a major projection from visual receptors; the first relay station in visual processing beyond the retina - Superior Colliculus is a visual pathway that does not travel through LGN. - 10% of retinal fibres project onto Superior Colliculus\...was thought the be "vestigial" system. - LGN = the "what" of vision - Superior Colliculus = the "where" of vision - For this reason, cortically blind patients sometimes demonstrate "blindsight" and can tell you where an object is, even though they claim they cannot see it. **(Orbitofrontal Cortex \[OFC\])** Receives direct and indirect information from **ALL** sensory areas. - Likely has important role in sensory integration. - May help assign motivational significance, allowing animals to make decisions about how to react to stimuli In sum, sensory processing occurs in **stages** with neurons responding to more and more complex aspects of the environment as information is transmitted to higher brain regions. **Blindsight:** A phenomenon in which individuals with cortical blindness are able to locate a visual stimulus; residual visual function with no awareness of this function Structure of The Eye/Retina/Photoreceptors ------------------------------------------ **Rods, Cones, and Retinal Ganglion Cells** - Rods and cones are photoreceptors at the back of the eye that detect light and colour - Rods = Better night vision - Cones = Better colour vision - Nocturnal animals tend to have far more rods than diurnal animals - Rods are 100x more sensitive to light than cones - Nocturnal animals navigate very well in the dark but often have inferior colour vision - Retinal Ganglion cells are neurons that are the "last stop" in the eye - Information from the photoreceptors in the retina is passed to the optic nerve and sent to the brain (Treat the below numbers as approximations, as slightly different numbers have been reported) **Humans (diurnal):** - 0.7-1.5 million retinal ganglion cells - 4.6 million cones - 92 million rods - Trichromat colour vision - Have densely packed cones in the fovea, which is responsible for sharp central vision **Dogs (arrhythmic diurnal... NOT nocturnal):** - 115,000 retinal ganglion cells (Peichl, 1992) - Far more rods than cones - Dichromat colour vision - Retinal ganglion cells arranged in "visual streak" Fechner's Law and Weber's Law ----------------------------- **Psychophysics:** The study of the relationship between sensations and perceptions; the relationship between the physical properties of a stimulus and the interpretation of that stimulus. - Conducted by asking participant to indicate when they see a light, hear a sound, smell an odor, etc. - ex: hearing tests - BUT\...animals can't make verbal responses\...so how do we test them? - Basically, we need to find a way to get a yes/no response from an animal. - The easiest way to do this is by training the animal to make one response when a stimulus is present (S+), and another response when the stimulus is not present (S-). **Ernst Weber (1795-1878)** - Noted that "in observing the disparity between things that are compared, we perceive not the difference between the things, but the ratio of this difference to the magnitude of things compared." - In other words,\...we are able to distinguish the relative difference, not the absolute difference between items. - **Weber's Law** - Weber\'s Law says that the size of the just noticeable difference (i.e., delta I) is a constant proportion of the original stimulus value. - Expressed as follows: 11*I* = *k I* - 11*I* is the difference threshold (or JND) - *I* is the intensity/magnitude of the standard - *k* is a constant, known as the Weber Fraction - The Weber fraction (k) is equal to 11***I / I*** **Gustave Fechner (1801-1887)** - Concerned with how a person's subjective experience could be measured scientifically - Student of Weber; created formal equations based on Weber's observations - **"Three Problems" of Psychophysics:** - **(1) Detection:** Find a way to measure the minimum amount of a stimulus that could be detected - i.e., absolute threshold - **(2) Discrimination:** Find way to determine how different two stimuli must be in order to be detected - i.e., difference threshold/JND - **(3) Scaling:** Find a way to describe the relationship between the intensity of the stimulus and the intensity of our sensation - i.e., [Fechner's Law] Absolute Threshold ------------------ - **Question:** How much of an energy change, starting from zero, is required for a subject to sense it? - Below some level of intensity, a subject will not be able to detect it. - As soon as the threshold intensity is exceeded, the subject can be expected to always detect it. - This is known as the **Absolute Threshold.** - **Absolute Threshold is not fixed!** What methods could we use to measure absolute threshold? 1. Method of constant stimuli a. Uses a fixed number of stimuli of various intensities b. Each stimuli presented many times in different orders c. Subject response "yes" when stimuli is detected and "no" when it is not d. S-shaped curve is usually found for all sensory systems when using method of constant stimuli 2. Method of limits e. Focus only on stimuli near the absolute threshold f. Descending series: Experimenter starts with easily detected stimuli, decreases intensity until subject can no longer perceive it. i. (Start above threshold, go down until stimulus not perceived) g. Ascending series: Experimenter starts with stimuli that cannot be perceived, increases intensity until it can be perceived. ii. (Start below threshold, go up until stimulus is perceived) 3. Adaptive testing (staircase procedure) h. Method of limits only test stimuli that bracket the absolute threshold (the last two in the testing series) \...all other stimuli in these sets tell us nothing. i. Adaptive testing keeps the test stimuli "hovering" around threshold by adapting stimuli based on subjects' responses. j. Threshold is obtained by averaging stimulus intensity value of the reversals. Difference Threshold -------------------- **Difference Threshold (or JND)** - Asks the question "by how much two stimuli must differ in order to be discriminated as not the same". - We are still measuring a threshold, but in this case, it is a threshold for the perception of a difference between the standard and comparison stimuli. **Just Noticeable Difference (JND):** The amount by which two sensory stimuli must differ in order for the difference to be detected. - JND is the amount by which two stimuli must differ so that the difference can be detected. - **As the intensity of a stimulus increases, so does the intensity that produces a JND** - (ex: a dim light turned up in a dark room is immediately noticeable, whereas a much brighter light will need much more illumination to produce a perceptual change). - The ratio between the current stimulus intensity, and the intensity change required for a JND is called the **Weber fraction.** **Differences in Discriminative Ability:** Better discrimination = smaller difference threshold, and steeper curve Methods of Detection -------------------- **Signal Detection** - All of the detection methods we have talked about so far involve responses of "yes I perceive it" or "no I don't perceive it". - Problem---what if the individual wants to appear more sensitive than they really are? - **Catch trials** can help eliminate this problem\...in these trials, no stimulus is presented. - **Signal Detection Theory** - Recognizes that any stimulus must be detected amongst a background of ongoing intermittent noise. - No absolute threshold, only a series of observations which must be categorized as "signal present" or "signal absent" - Can be used to determine how sensitive individual is to a signal, independent of any expectation effects that might bias decisions. Top-Down vs. Bottom-Up ---------------------- **Gestalt Principles** are considered "Top Down" processing **Gestalt Psychology** - Elemental theories of perception seem at odds with human experience, in which the sensory world is perceived as "whole" - Gestalt psychologists proposed instead that individuals perceive sensory information in its entirety and then divide in into elements if further processing is required. - Founded by Köhler, Wertheimer, and Koffka **Structuralism and Feature Integration Theory** are considered "Bottom Up" processing **Structuralism:** The idea that perceptions are built from elements of sensations - Discussed by Wundt (1832-1920) but mostly developed by Edward Titchener (1867-1927). - Theory holds that perceptions are created by combining or adding up elements of sensations. - Ex: For vision, visual stimuli are coded in different groups of neurons that convey this information, in parallel to higher brain regions. - When neural signals arrive at a new brain site, the information is recombined and transmitted to other parts of the brain. **Feature Integration Theory:** A modern version of structuralism which posits that the elements of sensory input are combined to produce perceptual wholes. - The main evidence for structuralism stems from the fact that the time to process two features (ex: colour and shape) of a stimulus is the sum of the time it takes to process the two individually. - This effect would not be expected if perception was synergistic. - **Feature Integration theory** is a modern version of structuralism. - It posits that elements of sensory input are coded at the initial stages of processing and then combined at higher levels to produce perceptual wholes. **Stimulus Filtering:** The process of separating and extracting meaningful (i.e., biologically relevant) information from the abundance and diversity of sensory cues in the environment - Both bottom up and top-down theories must account for **stimulus filtering**\...the process of separating and extracting meaningful information from the many sensory cues in the environment. - Ex: Humans can hear a spectrum of sounds but are acutely sensitive to those used in speech. - Stimulus filtering in animals is accomplished by **sign stimuli**, the essential features of a stimulus which are necessary to elicit a specific behavioural response. **Sign Stimulus:** The essential feature of a stimulus that is necessary to elicit a response; sometimes called a releaser - Responses to sign stimuli are typically species-typical behaviours that occur in a fixed order - Ex., red dot on herring gull bill, red belly on stickleback males, egg-rolling responses in geese - Because they reliably produce species-specific behaviours that promote survival, they are sometimes called **releasers** Unit 3: Memory ============== Chapter 3 -- Memory A diagram of memory Description automatically generated **Memory:** The mental processes of acquiring and retaining information for later retrieval; measured as the modification of behaviour based on past experience. Attention --------- **Attention:** The mental process that selects sensory information for further processing; a focusing on a particular stimulus or event - Attention is difficult to quantify - Tended to be ignored in early S-R learning promoted by behaviourists. - Nonetheless, many psychologists recognized that attention likely had important implication for many cognitive processes, particularly memory. - With the rise of cognitive psychology, greater interest in attention occurred. Attention Summarized: - **Selective attention** is the ability to attend to a limited range of sensory information, and is aided by mental search images - **Sustained attention** is the ability to maintain focus on one aspect of the environment for an extended period of time - This aids animals in remaining vigilant in watching for predators or prey - Selective and sustained attention in opposition to **divided attention**, which allows an animal to process input from more than one source at a time ### Selective **Selective Attention:** The ability to attend to a limited range of sensory information while actively inhibiting competing input - Selective attention is the ability to attend to a limited range of sensory information while actively inhibiting competing input. - A well-known example is the "cocktail party effect" - Eye tracking experiments show adaptive importance of selective attention---ability to focus on eyes (rather than whole face) allows one to recognize *anger, fear, or friendliness* very quickly. - Tinbergen (1960) proposed the idea of a search image---a mental representation of a target formed by foraging animals. **Search Image:** A mental representation of a target; foraging animals scan the environment for stimuli that match the search image ### Sustained **Sustained Attention:** The ability to focus on one aspect of the environment for extended periods of time - Sustained Attention allows animals to focus on one aspect of their surroundings for an extended period of time. - Measured in both humans and animals using a vigilance task. - Subjects are required to monitor a particular location and to indicate when a target stimulus has been presented. - Both humans and animals show wide variability in sustained attention. - Important implications in the wild for vigilance/watching out for predators (easier for animals in social groups). ### Divided **Divided Attention:** The ability to process, simultaneously, sensory input from more than one source - Divided attention is the ability to process sensory information from more than one source simultaneously. - Allows us to do more than one task at once, although usually one or both tasks will suffer. - Dukas & Kamil (2000): Blue Jays locate prey better when they can focus on one target, rather than dividing attention between two targets. - Feeding guppies are slower to react to predators than resting guppies (Krause & Godin, 1996) - **Almost all cognitive processes are compromised when attention is divided between too many sources.** Cognitive Maps -------------- - One possibility is that the rats are making a mental list of the arms they have visited. But rats are good at this task even when the maze has 16 arms (Cole & Chappell-Stephenson, 2003), so this seems unlikely. - More likely that the rats are using a mental "map" or representation of how the maze is arranged. - They could then use this **cognitive map** to navigate the maze (O'Keefe & Nadel, 1978). - **Beacons, landmarks, and geometric cues** are all also helpful tools which can help an animal navigate within this map. Stages of Memory ---------------- What we remember and how well we remember it depends on all three of these processes 1. **Encoding:** The first stage of memory processing in which incoming information is converted into neural signals that are used for later processing a. The conversion of incoming information into neural signals that will be used for later coding. b. Memory depends on us experiencing an event and having recorded some memory of that event. c. We **do not keep a perfect/literal record of this event**, rather, our experiences are coded in our nervous system. d. Not every piece of sensory info becomes a memory i. Attention plays key role here! e. **Elaboration:** The process of adding meaning, images, or other complex information to incoming sensory input such that encoding is enhanced ii. Enhances encoding iii. The process of adding meaning, images, or other complex information to sensory input iv. The greater the level of processing, the more durable the encoding v. Ex., tagging a visual image to a person's name (Mark = image of "X" on chest) vi. Difficult to know whether this is a uniquely human trait (can't ask animals if they do this) f. **Chunking:** A process that increases encoding capacity by reorganizing discrete elements of sensory input into larger units vii. One of the criticisms of encoding is that there is a limit on the amount of information that the nervous system can process viii. Miller (1956) suggested that we increase memory capacity by reducing the amount of information that is encoded through **chunking** g. Better encoding leads to better memory! ix. Encoding is not a passive transfer of information x. It is an active mechanism, and is facilitated by cognitive processes such as *attention, elaboration, and chunking* 2. **Consolidation:** The second stage of memory processing in which encoded representations are modified to become more stable over time h. Two components: **Rehearsal & Retention** (important in working memory) i. **Rehearsal:** Refers to keeping information in an active state, so that it is readily available for use (ex., remembering a phone number) xi. Accuracy of recall can be modified by cues indicated that something should or should not be remembered (Johnson, 1994) 3. **Retrieval:** The third stage of memory processing in which stored information is accessed j. Retrieval occurs when stored information is recovered so that it can be used to guide behaviour. k. Two mechanisms by which items are retrieved: **recognition** and **recall.** l. **Both recognition and recall are better if they occur in the same context in which the memory was encoded.** m. Retrieval processes are triggered by **retrieval cues.** xii. These act as reminders\...if you are discussing what you did during reading week last year with your friends, what they say will trigger other memories of what you did that week Proactive/Retroactive interference ---------------------------------- - Failures of memory do not always reflect the loss of previously learned information. - "Forgetting" is often not the irreversible loss of information, but rather some other mechanism that **interferes** with retrieval. The most common sources of memory disruption arise from exposure to prominent stimuli either before or after the event you are trying to remember. - **Proactive Interference:** Occurs when memory is disrupted by exposure to stimuli **before** the event to be remembered. - Clark's nutcrackers were allowed to watch the experimenter hide a seed in one of 176 cups of sand in a plywood board. - A total of 5 seed hidings were given each day during training. - Testing for proactive interference involved giving each bird one of **two types of trials** on alternate days. - On ***single list days,*** the birds watched the experimenter hide 5 single seeds. - Five minutes after the last seed was hidden, 5 recovery tests were given, one for each seed. - During each recovery test, 6 of the 176 holes were open to access. - Within each cluster of 6 open cups, one cup was the correct cup while the remaining cups were incorrect. - **These were the control trials used to test spatial memory without proactive interference.** - To assess proactive interference, ***birds were given this task twice a day***\...except in these trials the set of correct cups was different for each set. - For some of the recovery tests for the second list, the 6-cup cluster did not contain a cup where a seed had been hidden in list 1. - These were control recovery tests to see how the bird performed when it had received a previous list, but that list did not conflict with the current recovery test. - For other recovery tests the **6-cup cluster included the correct cup for the current list, a correct cup from list 1, and 4 incorrect cups.** - If proactive interference occurred, it was expected that there would be more **errors on the recovery trials that included a correct cup from list 1, and those errors would be more likely to occur to the cup in the cluster that had been correct in list 1.** - Animals performed well on two list recovery trials that did not contain an interfering cup **(red cup cluster),** but performance was worse on recovery trials with an interfering cup **(green cup cluster)** with the errors most often occurring to the wrong cup from list 1. - **Retroactive Interference:** Occurs when memory is disrupted by exposure to stimuli **following** the event to be remembered. - Retroactive interference can be studied using **Delayed matching to sample (DMTS),** by **presenting a stimulus during the delay interval** before the animal is given comparison test stimuli. - Roberts & Grant, 1978: the delay interval between sample and comparison stimuli normally occurred with no illumination in the chamber. - For the interference manipulation, the chamber was illuminated during the delay interval. - If the delay interval was short, there was very little retroactive interference. - If the delay interval was long (longest studied was 12 sec) performance dropped to chance levels. - Presenting an auditory stimulus during the delay has a similar effect, although the **retroactive interference effect is greater if the interfering stimulus is in the same modality as the sample stimulus (i.e: light, in this example)** - Retroactive interference is thought to be due to disruption of rehearsal of target information by the subsequently presented interfering information Directed Forgetting ------------------- - Studies have shown that the accuracy of recall can be modified by cues indicated that something should or should not be remembered (Johnson, 1994) - **Directed forgetting occurs when a stimulus (a forget cue) indicates that working memory will not be tested on that trial** Reference vs. Working Memory ---------------------------- **Reference Memory:** Long-term memory, involves encoding, consolidation, and retrieval of information in long-term store - Long-term retention of information necessary for the successful use of incoming and recently acquired information - Usually involves learning over repeated trials - Ex., remembering what ingredients go in a stew **Working Memory:** The process of maintaining information in short-term store so that it can be used in other cognitive processes - Is operative when information has to be retained only long enough to complete a particular task, after which the information is best discarded because it is no longer needed or because it may interfere with successful completion of the next task. - Ex: Remembering which ingredients you have already added in a recipe for stew. - **All successful working memory requires appropriate reference memories.** - Like RAM on a computer ### Delayed Matching to Sample Task - Initially developed to study working memory for visual cues in pigeons (Blough, 1959) - "Delayed matching to sample is the most frequently used procedure in the study of nonhuman short-term remembering" (White, 2013) - **Typically thought of as test of working memory, but in fact also requires reference memory** - Has since been adapted to study a number of different stimuli and species - First, subject is presented with a sample stimulus. - This sample stimulus will be the correct response at the end of the trial - Stimulus is then removed for a retention period - Subject is then given a memory test with two choices, one of which is the original sample stimulus - Choice of the sample stimulus is reinforced with a reward - **Requires both working and reference memory for successful completion** - Working memory helps the subject retain information about the sample stimulus, until it can be compared to the test stimulus - Reference memory allows the subject to remember the structure of the task from trial to trial - Has been used to study how animals remember shapes, number of responses performed, presence or absence of reward, the spatial location of stimuli, and the order of two successively presented events - Not all procedures are equal! - Several factors affect accuracy of recall: - The *nature of the stimuli used* - *Amount of time* subject is exposed to sample - *Length of the delay* after viewing the sample - Generally, memory is best the longer the sample stimuli is presented. - The longer the delay between the presentation of the sample stimuli and the choice task, the more mistakes are made. **Milmine, Wantanabe, & Colombo (2008)** - Pigeons tested in operant conditioning chamber with three keys in a row **(Delayed Matching to Sample Task).** - Middle key displays sample stimulus (red or white light) - Side key used during memory test (must peck key that matches sample stimulus) - **Remember trial: "I need to study the sample because there will be a test"** - **Forget trial: "There is no test, so I don't care about studying"** - **Free-reward trial: "There's no test, but I get food!"** - **Forget probe trial: Probe (test f-cue condition)** - **Free-reward probe trial: Probe (test free-reward condition)** - In R-cue trials, pigeons remembered the stimulus and matched correctly in the choice task. - In F-cue trials, pigeons performed poorly on the choice task (the F-cue disrupted memory). - Pigeons also did well with the F-r cue\...the anticipation of reward seems to have facilitated memory. Declarative vs. Non-Declarative Memory -------------------------------------- - **Non-Declarative memory** is an umbrella term to describe types of memory that do not depend on awareness on explicit knowledge to be expressed. - *Includes Sensitization/Habituation, Perceptual priming, Classical conditioning, Procedural Memory.* - **Declarative memory** is a knowledge-based system that is expressed through explicit statements "ex: I remember when\..., I know that\..." - *Includes Semantic memory, Episodic memory.* ### Non-Declarative **Non-Declarative Memory:** A subcategory of reference memory that does not depend on awareness or explicit knowledge to be expressed - Most simple type of non-declarative memory. - **Habituation** develops to stimuli with **low motivational significance**\...allows organisms to filter out irrelevant information so they do not waste time or energy responding to a benign stimulus each time it is encountered. - **Sensitization**, in contrast, develops to **motivationally significant events** (ex: a loud noise, which may be paired with a shock). - Typically studied in animals through startle responses. - Both occur in many situations, but always require repeated exposure to a stimulus #### Sensitization/Habituation **Sensitization:** Increased responding to repeated presentation of a stimulus that is often discussed in terms of reflex modification; a type of non-declarative memory **Habituation:** Decreased responding to repeated presentation of a stimulus that is often discussed in terms of reflex modification; a type of non-declarative memory - Very useful as an experimental paradigm in both human developmental psychology as well as animal cognition studies - Typically compares amount of time subject spends staring at a familiar versus a novel stimuli #### Priming **Perceptual Priming:** Facilitated identification of a stimulus as a consequence of prior exposure to the stimulus; a type of non-declarative memory - The facilitated identification of a stimulus as a consequence of prior exposure to the stimulus - Functions primarily at the **unconscious** level - Birds are better at detecting prey in a visual search task if item appeared in previous trials (Pietrewicz & Kamil, 1981) #### Procedural Memory **Procedural Memory:** The process underlying a gradual change in behaviour based on feedback; a type of non-declarative memory - A gradual change in behaviour based on feedback - We use this when we tie our shoes, comb our hair, or play a musical instrument - Assessed in animals most frequently using operant conditioning tasks - In most cases, performance improves with training (ex: rats running through mazes or lever pressing) #### Classical Conditioning - One of the principal categories of associative processes - Process by which a previously neutral stimulus, through pairing with a motivationally significant event, acquires the ability to elicit a response - Ex., Bell paired with food comes to elicit salivation in Pavlov's dogs ### Declarative **Declarative Memory:** A subcategory of reference memory; a knowledge-based system that is expressed through elicit statements and depends on conscious awareness. #### Semantic **Semantic Memory:** A subcategory of declarative memory describing general knowledge of the world - Tulving (1972) was the first to suggest that declarative memory should be divided into knowledge of *facts* and knowledge of *episodes.* - Knowledge of facts is known as **semantic memory.** - It describes general knowledge of the world that is not tagged to a particular event. - Includes knowledge of words and their meanings as well as concepts (ex: gravity) #### Episodic-Like Memory **Episodic Memory:** A subcategory of declarative memory describing knowledge for events in a personal past - Knowledge of episodes is known as **Episodic Memory** - It involves knowledge for events in a personal past - This autobiographical information is unique to each individual as it is associated with a particular time, place, and event - Has been a highly contentious topic in animal cognition! **Hyperthymesia:** Enhanced autobiographical memory - The food caching/recovery paradigm has also become very popular in asking questions about episodic memory in animals. - Episodic memories are very rich in detail\...they tell us **what, where**, and **when** something happened. - Also involves a phenomenological component\...the **conscious awareness (or autonoetic consciousness)** that an event was in the past and that you are now remembering it (Tulving, 1983). - Episodic memory was originally described by Endel Tulving (1983) and was considered to be a uniquely human trait (because of the component of awareness). - Unlikely to be able to determine whether or not non-human animals have the conscious awareness component of episodic memory\...**but we CAN study the what, when and where components of episodic memory.** - We refer to this **"episodic-like"** memory. - Food caching/recovery is an ideal way to study episodic-like memory, as we can easily manipulate the what/where/when components of memory. ##### Clayton & Dickenson (1999) - Varied palatability of food in Western Scrub Jays (peanuts vs. meal worms) - Question: Will birds care/remember *what* is stored *where*, based on *when* they are allowed to retrieve it? - Birds were allowed to cache both peanuts and meal worms in ice cube trays. - This is followed by a retention interval of 4 or 124 hours. - After 4 hours, both foods are still good\...but after 124 hours worms are decayed! - Birds learned to recover mealworms after a 4-hour retention interval, but peanuts after the 124-hour retention interval - As a control, a replenish group was used - In this group, fresh worms were always provided after the 124-retention interval - These birds always searched for worms as a result! Unit 4: Associative Learning ============================ Chapter 4 -- Associative Processes Classical Conditioning ---------------------- *Most simple* mechanism whereby organisms learn about the relations between one event and another. Enables both humans and non-human animals to take advantage of orderly sequences in the world: - Your car does not run unless the ignition has been turned on. - You cannot walk through a door until its opened. - It does not rain unless there are clouds in the sky. **Pavlov's Experiment** Involved 2 stimuli: the first was a **light or tone** that does not elicit salivation at the beginning of the experiment (a neutral stimulus); the second was a **food** or the taste of a sour solution which was placed in the dog's mouth -- this would elicit vigorous salivation even the first time it was presented. - **Unconditioned Stimulus (US):** Food → **Unconditioned Response (UR):** Salivation. - **Neutral Stimulus (NS):** Bell → No salivation. - After repeated pairings of NS + US: - **Conditioned Stimulus (CS):** Bell → **Conditioned Response (CR):** Salivation. **CS:** Previously neutral stimulus that acquires significance. **US:** Naturally elicits a response. **CR:** Learned response to the CS. **UR:** Reflexive response to the US. **Unconditioned Response (UR):** In classical conditioning, a response that is elicited prior to conditioning. **Unconditioned Stimulus (US):** In classical conditioning, a stimulus that has motivational significance prior to conditioning. **Conditioned Response (CR):** In classical conditioning, a response that is elicited by the CS following conditioning. **Conditioned Stimulus (CS):** In classical conditioning, a stimulus that acquires motivational significance through pairing with the US. ### Fear Conditioning/Conditioned Suppression - **John Watson & Rosalie Rayner (1920):** \"Little Albert\" experiment demonstrated conditioned emotional responses. - Assumed "There must be some simple method by means of which the range of stimuli which can call out these emotions and their compounds is greatly increased" - The "simple method" they spoke of is Pavlovian conditioning. - Albert learned to fear a white rat, and the fear generalized to similar stimuli (e.g., white furry objects). - **Ethical concerns:** Albert's true identity remains debated, and proper debriefing never occurred. - "Albert" was not healthy, possibly neurologically impaired and died at age of 6. - His mother may have been an employee of the hospital where the research took place, possibility of coercion. *"Give me a dozen healthy infants, well-formed, and my own specified world to bring them up and I'll guarantee to take any one at random and train him to become any type of specialist I might select -- doctor, lawyer, merchant-chief, and yes, even beggerman and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors."* Watson (1930) **Fear in Non-Human Animals** - **Freezing in Rats:** Rats display fear by remaining motionless (i.e., freezing) when a conditioned (CS) stimulus (e.g., light/tone) predicts an aversive (US) stimulus (e.g., shock). - Freezing: immobility of the body (except for breathing) and the absence of movement of the whiskers associated with sniffing. - Probably evolved as a defensive behaviour -- less likely to be caught by predators if they are motionless - When animals freeze, they stop lever pressing. - Number of lever presses during CS vs. number of presses during non-CS period is a measure of conditioned fear. - **Conditioned Suppression:** Fear reduces ongoing behaviors, such as lever pressing. - **Suppression ratio =** LP during CS / (LP during CS + LP during pre-CS period). - **Lick-Suppression Procedure:** Fear CS (e.g., tone) delays drinking behavior. - **Bar-Press Suppression:** Rats can be trained to press a lever for food reward. - Tone or light is then paired with brief shock. - As subjects acquire the conditioned fear, they suppress lever pressing during the CS. ### Sign Tracking vs. Goal Tracking Individual differences in sign tracking have been shown in rats. - Rats placed in chamber with food cup in the middle of the wall. - Lever inserted through slots on either side of the cup. - Lever = CS. - Food delivered to cup = US. - For each conditioning trial, lever is inserted/withdrawn, followed by delivery of food. - Rats then tested in trials in which no food is delivered. - **Sign tracking measured by contact with lever (CS).** - **Goal tracking measured by contact with food cup (US).** **Sign Tracking** - Pavlov's research originally dealt with salivation and highly reflexive responses, which encouraged the belief the classical conditioning occurs only in reflexive response systems. - This restrictive view of Pavlovian conditioning has since been abandoned. This is because of more complex paradigms like [sign tracking] (aka [autoshaping]). - **Sign tracking is investigated in the laboratory by presenting a discrete, localized visual stimulus just before the delivery of food.** - Organisms approach stimuli that signal food availability. - **Example:** A quail approaches a wooden block predicting the presence of a female instead of the actual location where she appears. - Is sign tracking *always* observed in Pavlovian conditioning? - NO. - **Individual Differences:** Some animals develop **goal tracking** (approaching the food cup instead of the signal). - Individual differences in sign tracking have been attributed to individual differences in impulsivity and vulnerability to drug use (Tomie, Grimes, & Pohorecky, 2008). - Greater activation of dopamine reward circuits. - **Sign tracking is thus a valuable model for studying learning processes and neural mechanisms that contribute to drug addiction.**  ### Learned Taste Aversion **Conditioned Taste Aversion (CTA):** An aversive reaction to the smell and taste of a particular food caused by a prior food-nausea association. - Unique type of classical conditioning where an organism learns to avoid a food that previously made them sick. - The sensory aspect of food is the CS (ex: wing pattern on monarch butterfly). - Exploited by viceroy, a form of mimicry. - These become associated with the consequences of eating (good or bad), which are the US. - Can occur **even if the illness occurs hours later** (unlike most classical conditioning, which requires immediate reinforcement). - **Example:** Rats given saccharin-flavored water and later exposed to radiation (causing nausea) avoided saccharin in the future. - **Species Differences:** - **Rats:** Generalists that sample food cautiously (neophobia). - Cannot clear their system of toxins by vomiting. - If it gets sick, avoids food in future. - **Vampire bats:** Specialists that consume only blood and cannot form taste aversions. ### Temporal Contiguity **Temporal Contiguity:** Closer CS and US timing generally strengthens learning (except in learned taste aversion). - i.e., **a US that immediately follows a CS and a response that immediately produces a reinforcer induce robust conditioning.** - Long delay before receiving reinforcement -- animals more likely to make associations with extraneous stimuli (Dickenson, 1980). - Does not account for all explanations in associative learning. - "superstition" in pigeons. ### Latent inhibition **Latent Inhibition:** A phenomenon in which prior exposure to a stimulus blocks or retards subsequent conditioning to this stimulus; also called CS pre-exposure effect. - Latent Inhibition: Pre-exposure to a stimulus (without consequences) slows later learning. - Basically...a familiar stimulus takes longer to acquire meaning as a CS than a new stimulus. - This is because organism first learns that CS has no motivational significance...they must then overcome this information in order to learn the association between the CS and the US. ### Rescorla-Wagner and Blocking Effect **The Blocking Effect** **Blocking:** A phenomenon in which an association between one stimulus and a US disrupts subsequent conditioning to a second stimulus when the two are presented in compound conditioning trails. **Phase 1:** Experimental group received pairing of stimulus A with US until association is formed (ex: bread pudding CS, illness US). - Stimulus B is then presented with stimulus A (ex: bread pudding with sauce) and paired with US (illness). - \*\*very little responding to stimulus B will happen when presented on its own, even though it is paired with US\*\* A group of words on a white background AI-generated content may be incorrect. **Rescorla-Wagner Model** - **One of the most influential models of learning.** - Learning occurs when there is a **discrepancy** between expected and actual outcomes. - Mathematical model for conditioning in which the prediction of the US for a trial can be represented as the sum of all the associative strengths for the CS present during the trial. - Utilizes notion of the importance of **"surprise"** in US. - **Mathematical Representation (learning depends on the level of surprise at the US):** - **ΔV = k (λ -- V)** - Where: - **λ -- V** = Level of surprise (the difference between what occurs (**λ**) and what is expected (**V**). - **ΔV** = Change in associative strength (learning on a given conditioning trial). - **k** = Constant (salience of stimuli -- CS and US). - **λ** = Maximum associative strength. - **V** = Current associative strength. - If you expect a new pair of shoes for your birthday and instead get a car, this would be an unexpectedly large US. - If you expect a car and get a pair of shoes, this would be an unexpectectedly small US. - **Rescorla & Wagner assumed that the level of surprise (i.e., the effectiveness of the US) depended on how different the US was from what the subject expected.** - Strong conditioning = Strong expectation of US. - Weak conditioning = Weak expectation of US. **How Does Rescorla-Wagner Explain the Blocking Effect?** **Blocking Effect Explanation:** If a stimulus (A) fully predicts the US, a second stimulus (B) adds no new information, preventing learning. - Recall that the first stimulus A in the blocking effect receives extensive conditioning so that it reliably predicts the US. - In other words, stimulus A has already reached the asymptote of learning (**λ**). - In Phase 2, stimulus B is presented together with stimulus A, and the two CS's are paired with the US, so **V = V~A~ + V~B~** - Because of Phase 1 training, V~A~ = (**λ**) at the start of Phase 2. - But V~B~ starts at 0. - So, **V =** **λ + 0, or λ.** - Therefore, stimulus B takes on no associative value in Phase 2, which results in the blocking effect. Operant Conditioning -------------------- **Operant Conditioning:** A change in behaviour that occurs because the behaviour produces a consequence (positive or negative). - **Operant Conditioning:** Method of learning that occurs through rewards and punishments for behaviour. - Encourages the subject to associate desirable or undesirable outcomes with certain behaviours. - Also known as **Instrumental Conditioning.** - Classical conditioning = Concerns how animals adjust their behaviour to elements of the environment that they do NOT control. - Operant conditioning focuses explicitly on their **goal-directed** or **instrumental** behaviour. - **Early investigations of operant conditioning -- Edward Thorndike (1898):** - **Law of Effect:** Response (R) in the presence of a stimulus (S) followed by **satisfying** event are reinforced, while response followed by an **annoying** event, the S-R association will be weakened. - \*\*key feature of this mechanism is that is compels the organism to make response R whenever stimulus S occurs. Explains many compulsive behaviours.\*\* - Ex., smell of popcorn (s) entices you to eat popcorn (r). - Studied problem-solving in cats using **puzzle boxes.** - Different boxes require different responses to get out. **Law of Effect:** Thorndike's idea that responses that produce a satisfying outcome will be repeated whereas those that produce unsatisfying outcomes will not. ### Four Quadrants **Positive Reinforcement:** A positive relationship between a response and an appetitive stimulus; presentation of the reinforcer increases responding. **Negative Reinforcement:** A positive relationship between a response and an aversive stimulus; removal of the reinforcer increases responding. **Punishment:** A negative relationship between a response and an appetitive stimulus; presentation of the reinforcer decreases responding. **Omission:** A negative relationship between a response and an aversive stimulus; removal of the reinforcer decreases responding. **Habit Learning (S-R Learning):** Responses that are elicited automatically by environmental stimuli and are relatively insensitive to changes in the value of the reinforcer. - **Reinforcement (Increases behavior):** - **Positive Reinforcement:** Adding a pleasant stimulus. - **Negative Reinforcement:** Removing an unpleasant stimulus. - **Punishment (Decreases behavior):** - **Positive Punishment:** Adding an unpleasant stimulus. - Also known as "punishment". - **Negative Punishment:** Removing a pleasant stimulus. - Also known as "omission". **Often referred to as the "four quadrants" of operant conditioning.** - Positive = Something added. - Negative = Taking something away. - Reinforcement = Increase in behaviour. - Punishment = Decrease in behaviour  ### Free Operant Procedure Involve **Discrete-Trial Procedures** or **Free-Operant Procedures.** - **Discrete-Trial Procedures:** Similar to Thorndike's procedure in that each trial begins with putting animal in apparatus and ends when they complete instrumental response. - Often involves maze learning. - Behaviour typically measured using **running speed** or **latency.** - **Free-Operant Procedures:** Allow the animal to repeat the instrumental response without constraint over and over again, without being removed from the experimental apparatus until the experimental session is complete. - Invented by B.F. Skinner (1938) to study behaviour in a more continuous manner than is possible with mazes. - Allows experimenter to observe variations in responding across time. **Conditioned Avoidance:** An operant paradigm in which animals learn to avoid a stimulus associated with an aversive event. - Unlike discrete-trial techniques for studying operant behaviour, free-operant methods permit **continuous** observation over long periods of time. - Therefore, the subject, not the experimenter, determines the frequency of response. - This allows us to observe **changes in the likelihood of response over time.** - The relationship between responding and reinforcement is determined by the **reinforcement schedule.** ### Schedules of Reinforcement **Reinforcement Schedule:** In operant conditioning, the relationship between responding and the rate of reinforcement delivery. **Continuous Reinforcement (CRF):** A reinforcement schedule in which every response produces a reinforcer; equivalent to an FR1 schedule. **Fixed Ratio (FR):** A reinforcement schedule in which a set number of responses produces the reinforcer. **Variable Ratio (VR):** A reinforcement schedule in which an average number of responses produces the reinforcer. **Fixed Interval (FI):** A reinforcement schedule in which reinforcement is delivered following the first responses that occur after a set period of time. **Variable Interval (VI):** A reinforcement schedule in which reinforcement is delivered following the first responses that occur after an average time interval has elapsed. **Ratio Strain:** Cessation of operant responding with high FR schedules. 1. **Ratio Schedules (Based on response count)** a. **Fixed Ratio (FR):** Reinforcement after a set number of responses. b. **Variable Ratio (VR):** Reinforcement after a variable number of responses (e.g., slot machines). c. **Progressive Ratio (PR):** Increasing effort required for each reinforcement. 2. **Interval Schedules (Based on time elapsed)** d. **Fixed Interval (FI):** Reinforcement after a fixed time (e.g., paycheck every two weeks). e. **Variable Interval (VI):** Reinforcement after an unpredictable time (e.g., checking for email responses). **Ratio schedules produce faster responses than interval schedules.** - **Post-Reinforcement Pause:** Common in fixed schedules; organisms pause before starting the next response cycle. +-----------------------+-----------------------+-----------------------+ | Schedule Type | Definition | Response Patterns | +=======================+=======================+=======================+ | **Fixed Ratio (FR)** | Reinforcement after a | **High response rate | | | set number of | with | | | responses | post-reinforcement | | | | pause.** | | | (e.g., FR5 = | | | | reinforcement after 5 | Longer pauses after | | | responses). | larger ratios. | +-----------------------+-----------------------+-----------------------+ | **Variable Ratio | Reinforcement after a | **Steady, high | | (VR)** | variable number of | response rate. No | | | responses, averaging | pauses.** | | | to a set value | | | | | Used in gambling | | | (e.g., VR10 = | (slot machines). | | | reinforcement on | | | | average every 10 | | | | responses). | | +-----------------------+-----------------------+-----------------------+ | **Fixed Interval | Reinforcement given | **Scalloped response | | (FI)** | for the first | pattern** -- slow | | | response after a | early responses, then | | | fixed time period | increased responding | | | | as reinforcement time | | | (e.g., FI2 = | approaches | | | reinforcement every 2 | | | | minutes). | | +-----------------------+-----------------------+-----------------------+ | **Variable Interval | Reinforcement given | **Steady, moderate | | (VI)** | for the first | response rate.** | | | response after a | | | | variable amount of | No predictable | | | time | pauses. | | | | | | | (e.g., VI3 = | | | | reinforcement on | | | | average every 3 | | | | minutes). | | +-----------------------+-----------------------+-----------------------+ **Key Findings from Reynolds (1975)** - **Study comparing VR vs. VI schedules in pigeons.** - **Result:** Pigeons on **VR schedules responded 5x more frequently** than those on VI schedules. - **Why?** - **Ratio schedules reinforce more responses per unit of time.** - In **interval schedules,** responding before the set time **doesn't increase reward rate**, leading to **lower response rates.** **Summary of Ratio vs. Interval Schedules** 1. **Ratio schedules produce higher response rates** than interval schedules because reinforcement is tied to behavior, not time. 2. **Variable schedules (VR & VI) lead to more consistent responding** compared to fixed schedules (FR & FI), which cause pauses. 3. **VR schedules (like gambling) create the highest and most persistent response rates.** **Equipotentiality:** The idea that associations between different stimuli, responses, and reinforcers could be formed with equal ease. **Adaptive Specialization:** The relative ease with which animals acquire certain associations, based on their evolutionary history. ### Superstition in Pigeons **B.F. Skinner (1948)** - **B.F. Skinner** conducted an experiment where pigeons were placed in a chamber and given food at **fixed intervals (every 15 seconds),** regardless of their behavior. - Findings: - Pigeons developed **random behaviors** (e.g., turning in circles, head bobbing) even though food delivery was unrelated to their actions. - **Skinner's conclusion:** These behaviors had been **accidentally reinforced,** leading to the idea of **superstitious behavior** in animals **Staddon & Simmelhag (1971): A Reanalysis of Skinner's Study** - **Objective:** Replicate Skinner's experiment but with more systematic observations. - **Findings:** - Pigeons **did not display entirely random behaviors** as Skinner suggested. - Instead, behaviors followed **predictable patterns,** categorized as: 1. **Terminal Responses** a. **Occurred near the end of each interval (right before food delivery).** b. Included **orienting toward the food hopper,** pecking near the food source. c. These behaviors **directly related to obtaining food**, suggesting they were **anticipatory actions,** not superstitions. 2. **Interim Responses** d. **Occurred in the middle of the interval, far from food delivery.** e. Included behaviors like **pacing, turning in circles, or pecking at the floor.** f. These were **not linked to reinforcement** but may be **species-typical foraging behaviors.** A graph of response probability AI-generated content may be incorrect. **R1=** Orienting toward food magazine (terminal response) **R7 =** Orienting towards magazine wall (terminal response) **R8 =** Moving along magazine wall (interim response) **R4 =** Making quarter turn (interim response) **R3 =** Pecking at floor (interim response) **Interpretation Using Behaviour Systems Theory (Timberlake & Lucas, 1985)** - **Superstitious behaviors are actually biologically-driven foraging behaviors.** - **Pigeons cycle between:** - **General search** (looking around, moving) when food delivery is distant. - **Focal search** (orienting to the food hopper) when food delivery is imminent. - **Post-food behaviors** immediately after eating. ***Why This Matters*** - Staddon & Simmelhag **challenged Skinner's explanation** of superstition by showing that the behaviors were not random but **structured responses tied to food anticipation.** - **Key takeaway:** Animals are not simply forming accidental associations; their behaviors are guided by **evolutionary patterns** of foraging and food-seeking. ### Extinction **Extinction:** Removal of a US that leads to a reduction in responding. **Spontaneous Recovery:** The reappearance of a CR following extinction. **Disinhibition:** The recovery of a CR following extinction when a novel stimulus is presented. **Response Renewal (Reacquisition):** Recovery of a CR following extinction when extinction is conducted in a novel experiment. - **Extinction in Classical Conditioning:** Repeated CS without US leads to response decline. - **Extinction in Operant Conditioning:** Withholding reinforcement leads to response decline. - **Spontaneous Recovery:** Extinguished response re-emerges after a delay. - Association is never "erased" or lost, however...a CR will reappear after extinction if there is a delay - This is known as Spontaneous Recovery - **Response Renewal:** Extinguished response returns if the CS is presented in a new context. - Extinction trials are context specific -- if extinction trials are conducted in a new context, response declines but will re-emerge when CS is presented in original context...This is Response Renewal - Renewal typically occurs as follows: - Acquisition training conducted in presence of contextual cue A - Participant then moved to context B for extinction training - When participants are moved back to context A, conditioned responding returns - **Disinhibition:** If a novel stimulus is introduced during extinction, animal will be distracted and start responding to new stimulus - Ex., dog with salivation CR to bell CS is given extinction training. Bell then presented with without food, and salivation declines. When bell is presented with new light stimulus, salivation recovers  Differences Between Classical & Operant Conditioning ---------------------------------------------------- Feature Classical Conditioning Operant Conditioning ------------------- -------------------------------- --------------------------------------------- **Response Type** Involuntary (e.g., salivation) Voluntary (e.g., pressing a lever) **Focus** Association between stimuli Association between behaviour & consequence **Reinforcement** Automatic Contingent on behaviour **Example** Pavlov's dogs Skinner's pigeons