Module 5 Chapter 9_ Memory.pdf

Module 5 Chapter 9: Memory Development Childhood Amnesia -coined by Freud; the inability to recall early childhood memories -there is little evidence that we can remember our early, formative experiences -most adults can recall very few memories from before 2-3 years of age; this often extends even...

Module 5 Chapter 9: Memory Development Childhood Amnesia -coined by Freud; the inability to recall early childhood memories -there is little evidence that we can remember our early, formative experiences -most adults can recall very few memories from before 2-3 years of age; this often extends even further into childhood Causes of Childhood Amnesia -Freud’s repression theory (discredited): childhood amnesia was the result of the active blocking of unacceptable impulses in early childhood -Development of a Sense of Self: -decline of childhood amnesia follows the onset of autobiographical memory! (ability to verbally recall memories of a personally experienced event) -this suggests the development of a self-concept (a self that is distinct from other people and the world) is an important part of allowing the infant to store, maintain, and retrieve memories about themselves -~18 months: Mirror-rouge task -> infants touch their nose when seeing their reflection in a mirror with a red dot on their nose (as opposed to touching the mirror). This shows they understand the mirror is a reflection of themselves and not another person (visual self-recognition) -5 months old: infants have been shown to prefer a video of another child over a video of themselves, suggesting visual self-recognition may occur earlier -Language Development: -~22 months: children acquire the ability to use personal pronouns = “I”, “me” -language development explains the inability to recall early memories that were encoded before language development -Shrinking Machine: in one study, 2-4-year-olds used the toy shrinking machine. 6-12 months later they were tested for memory via verbal recall; not once did a child use a word to describe the event that wasnt in their vocab at the time of the event -no evidence of verbal recall for aspects of the event that were encoded behaviourally; language cues only effective for retrieving memories encoded in language -the way that parents talk to their children about past events influences how children report memories when they start talking about the past -proposed that children are taught and encouraged to generate narratives during the social discussion of joint memories -they learn to use another’s conversation as a retrieval cue for past events -> allows for repeated memory retrieval and maintenance over time -first-born children tend to have memories 3-5 months earlier than later-born children, possibly because there is more child-parent interactions with first borns = first-borns have more opportunity for verbal rehearsal of previously experienced events -individualistic cultures and cultures that emphasize verbal recounts of past personal experiences report earlier memories than interdependent cultures Infantile Amnesia -defined by more rapid forgetting in infancy than later in life -older rat pups showed a retention of fear more than younger rat pups -> our explanations for maturational changes in memory processing must be applicable across species -neurological immaturity to explain infantile amnesia? An infant may be unable to store info in an accessible form -hippocampus and other brain structures are present and functioning in childhood BUT maturation in connections between regions likely needs to develop over time Assessing Memory in Infants -in adults, we can measure when language ability became proficient enough for us to retrieve and report memories by simply asking them to verbally recall memories -in infants, memory has to be inferred as a behavioural change following a specific learning experience Procedures for Studying Memory Development 1) Visual paired comparison task -habituation and subsequent preferences for novel stimuli -a familiarized stimuli is paired with a novel stimuli; memory is inferred if the infant shows a preference for the novel stimuli after some time between familiarization and recognition test 2) Operant conditioning 3) Deferred imitation -experimenter performs a series of novel actions -> infants ability to reproduce novel actions is assessed either immediately or after delay -compared to the actions of infants who havent seen the task performed before the test (“control condition”) -helps understand the level of spontaneous infant activity (what the infant would do already having not seen the experimenter perform it) -work by inserting a delay between the learning and memory retrieval phases; duration of delay depends on task and infant age -memory is inferred when past experiences influence present behaviours Recognition and Recall -recall memory: info retrieval that occurs in the absence of any cues or prompts to aid the process -deferred imitation measures recall memory since the infant must reproduce the action all on their own with no action cue -recognition memory: info retrieval involving judging whether a stimulus or event has been experienced before -VPC How Long are Events Remembered for in Infancy -older infants remember for longer periods of time than younger infants -operant conditioning: 2 month olds -> one day, 9 month olds -> 6 weeks, 18 month olds -> 13 weeks -deferred imitation: both 6 and 9 month olds imitated the action when tested immediately, BUT only 9 month olds showed imitation after a 24-hour delay -24-month olds showed retention after a 3 month delay; 18 month olds showed retention for only 2 weeks -9 month olds can can remember and reproduce actions from a 2-step sequence after a month delay BUT the long term memory for the SEQUENCE of events is still developing -10 months: infants can remember the sequence from a two-step event after one or two months of delay -after a six month delay, 10 month olds can remember the actions but NOT the sequence of two-step events -evidence of long-term recognition at the behavioural level also present for at the neural level (diff neural activity for familiar and novel sequences) -infants with a longer gestation period exhibit greater memory retention than infants of the identical age that had a shorter gestation period Different Techniques Give Different Results -we cant yet say for how long an infant of a particular age will remember a specific event -lots of variation across procedures in the events that occur during learning and retrieval; this makes it hard to draw general conclusions across paradigms and in real life -mutliple measures are essential to allow us to identify developmental memory changes at a general level rather than paradigm-specific memory changes Are Infant Memories More Impoverished Than Adult Memories? Infant Memories can be Highly Specific ★ unlike early verbal memory reports (which are general rather than specific), infants’ memory representations as assessed by behavioural techniques are highly specific ○ What does this mean?? For example, in a deferred imitation task, an infant shown the target task with a cow and then later given a duck to perform the same task will not be able to do it. Memory is disrupted with the change of specific traits and details. This can happen at 2 months of age ○ This extends to the environments and even odours where learning occurs; seen in operant conditioning with 3 month old infants. Also observed in VPC and deferred imitation What Causes Age-Related Changes in Retention? ★ Additional cues in the environment are available with age ★ Infants become better at generalizing across environments and target objects with age ★ Language development provides additional cues and helps with retrieval and retention by verbally rehearsing memories ○ A 2 year old talking herself through the events of the day before she goes to sleep Brain Development ★ Multiple events make up a single memory ○ Encoding, storing, and retrieving memories is complex, so multiple brain areas are involved and it is hard to pinpoint one area that is responsible for one type of memory Medial temporal lobe -> hippocampal formation and parahippocampal gyrus (lower-middle portion of the brain) = important for long-term info storing Could development and maturation of these structures be responsible for differences in memory observed between two age groups? ○ Hippocampal memory structures have been shown to be essential for memory performance on deferred imitation tasks Visual Recognition Memory ★ One of the most thoroughly researched memory aspects assessed during first 2 years of life -> visual recognition memory of pictures or events as measured in VPC (and others) ○ Principle structures involved in visual recognition memory = rhinal cortices and hippocampal formation (part of medial temporal lobe) Maturation of Brain Structures ★ Studies show that the hippocampal structures are anatomically more mature at birth than once thought; its not firmly concluded they are as functionally mature as they are anatomically mature ★ Inferior temporal cortical areas arent adult-like until 12 months, but function before this age ○ Research in monkeys suggests age related changes in memory across infancy may reflect slow maturation of cortical areas instead of hippocampal?? ★ Visual recognition in infants may involve the adult hippocampal structures (mature) but the way visual info reaches this area is diff in infancy (function) ○ This might be why early episodes cant be remembered; the visual pathways used to create them dont exist anymore in adulthood? Why is Retention in Experimental Studies So Short? ★ Real life affords the infant more stimuli to help with encoding as opposed to the experimental environment ○ Voice has to be presented with the face for the face to be recognized as the mother’s ○ In real life, stimuli is presented in more than one environment under more than one condition (presence of mother and favourite toy in varying instances) Learning and Memory Abilities Depend on How They Are Tested ★ Limited motor abilities in infants pose a challenge for studying memory ★ No evidence of memory should be first be ruled out as a behavioural limitation before we call it a cognitive limitation ○ Age-appropriate behaviours need to be used when assessing memory ★ A preference for a familiar stimulus after a long delay in the VPC task might also STILL be an indication of memory! ○ Infants preferences may change from: novelty preference -> null preference -> familiarity preference over 1 month after habituation ★ Emotional salience of the stimuli may predict how or if the memory will be expressed ○ 5 month olds in the still face experiment showed evidence of memory up to 15 months later when the visual episode involved an emotional component between themselves and the mother What Type of Long-Term Memory System Do Infants Have? ★ Two diff kinds of long-term memory: ○ Declarative: memory for events (episodic) and facts (semantic) Medial temporal lobe structures (hippocampus and surrounding) Procedural memory can survive damage to these structures ○ A patient may not want to shake a researcher’s hand after being pricked with a tack, but cant remember why ○ Procedural: memory for habits and skills ○ Both memory systems may be present at birth, although declarative may be immature (predeclarative) ○ Immaturity of cortical inputs to the hippocampus ~9 months: the declarative memory becomes like that of an adult ★ The nature of infant memory systems in relation to adults needs more testing and better paradigms