Memory Development and Information Processing Theory

Perceptual Narrowing and Multimodal Integration Recap

• The lecture begins with a review of a study examining the link between perceptual narrowing and multimodal integration during the first year of life.

• Multimodal integration refers to how an individual combines signals from different sensory modalities, such as auditory (hearing) and visual (seeing).

• Study findings regarding age groups:

  • Newborns: They are capable of pairing a novel sound (e.g., cooing or grunting) with a face that corresponds to the production of that sound at above-chance levels.

  • 4-month-olds and 12-month-olds: This capacity diminishes or is no longer expressed.

• Interpretation: Perceptual narrowing occurs as infants become less able to discriminate between non-relevant categories, such as monkey faces. Because monkey faces are not a relevant category for growing human infants, they cease pairing visual and auditory information for them as they did when they were newborns.

The McGurk Effect: A Demonstration of Multimodal Integration

• The McGurk effect is a robust demonstration of how visual information drastically impacts auditory perception.

• In the video demonstration, the audio track remains exactly the same throughout (a looping sound), but the perceived sound changes based on the visual of the speaker's mouth movements.

• Participants often report hearing "thaw" (or "fa") when looking at one face and "ba" when looking at another, even though the auditory signal is identical.

• Theoretical Advantage: This bias is considered advantageous for language processing in noisy environments. If a mouth movement looks like an "F" sound, the brain interprets an otherwise ambiguous auditory signal as such.

• Key Takeaway: Auditory perception does not function like a microphone, and visual perception does not function like a camera; they integrate in complex and sometimes counterintuitive ways.

Developmental Influences on Taste Preferences

• Taste preferences are highly flexible and significantly impacted by early exposure, both in utero and through direct intake.

• Formula Feeding Study:

  • Group 1: Infants given a bitter-tasting formula.

  • Group 2: Infants given a milk-based, sweeter formula.

  • Observation at $7\,months$: When presented with the alternative formula, infants tried the bitter version for the first time showed extreme distaste (negative facial expressions), while infants previously exposed to it were "totally happy."

• Prenatal Influence: Research suggests that the foods mothers consume during pregnancy can impact the taste profiles and preferences of the child later in development.

• Media and Popular Press: Some articles discuss these findings in a "dystopian" light, suggesting children can be born essentially "addicted" to junk food based on maternal diet.

Information Processing Theory and the Computer Metaphor of Mind

• The central metaphor of Information Processing Theory is that the human mind functions like a computer.

• Characteristics of processing: Serial, feed-forward, and stage-based.

• The Three-Stage Process:

  • Input: Information entering the system via perception (analogous to computer inputs).

  • Computation: The application of rules and representations to information (cognition).

  • Output: The generation of an action or display (analogous to a computer screen or printout).

• Shared Terminology: Development and cognitive psychology borrow terms from computer science, including encoding, storage, and retrieval.

• Hardware Analogy: Researchers in this tradition aim to create a "wiring diagram" for the human brain (e.g., mapping visual processing centers in macaque monkeys and humans) to understand how information travels through different components, similar to a motherboard.

• Theoretical Orientation: Information Processing Theory focuses on domain-general changes. As the "hardware" (brain) develops through factors like myelination, the whole system receives a processing boost, improving memory and learning across the board.

The Atkinson and Schifrin Model of Memory

• This influential model describes the flow of information through different memory systems:

  • Sensory Memory: Holds information for a very brief duration.

    • Iconic Memory (visual): Lasts approximately $0.5\,seconds$.

    • Echoic Memory (auditory): Lasts a few seconds.

  • Working Memory (Short-Term Memory): Actively held information with a limited capacity.

    • Duration: Generally lasts about $15\,seconds$ unless actively maintained (rehearsed).

    • Capacity: Limited (the "set number of slots" metaphor).

  • Long-Term Memory: Information stored for extended periods with no known upper limit.

    • Explicit/Declarative Memory: Recallable facts (e.g., the capital of New Zealand) and life episodes.

    • Implicit/Non-declarative Memory: Skills and procedural knowledge (e.g., riding a bike) and classical conditioning.

• System Processes:

  • Encoding: Building a representation of attended information in working memory.

  • Storage: Maintaining information in working or long-term memory.

  • Retrieval: Reactivating information from long-term memory into working memory.

  • Attention: Functions like a "spotlight" or "torch." It is used to keep information active in working memory or to "search" for information in long-term memory.

Detailed Components of Working Memory

• Working memory is often broken down into three specialized subsystems overseen by a controller:

  • Phonological Loop: Holds a limited number of sounds for a short period. It is associated with "subvocalization" (the inner voice while reading) and remembering tunes.

  • VisioSpatial Sketchpad: Actively maintains visual and spatial information, such as imagining a map while navigating or picturing a face like the Mona Lisa.

  • Episodic Buffer: Replays specific experienced events or imagines future hypothetical events. It integrates visual, semantic, sounds, and smells into a rich experience (e.g., a dancer mentally practicing movements).

  • Central Executive: The "orchestrator" or "executive controller." It prioritizes information, makes judgments on what matters, decides on encoding strategies (like repeating a phone number), and manages limited attention resources.

Childhood and Infantile Amnesia: Explanatory Factors

• Childhood amnesia is the phenomenon where adults generally cannot recall specific autobiographical events from before the age of approximately $2.5$ to $3\,years$.

• Possible contributing factors (Six Factors):

  1. Working Memory Capacity: Infants may lack the capacity to hold enough pieces of information (people, events, goals, narratives) simultaneously to consolidate them into long-term memory. Functional linkage to the prefrontal cortex for working memory increases at $4$ to $5\,years$ of age.

  2. Language Development: Language provides "efficient descriptors" or summary points that cue memories.

     • The "Incredible Shrinking Machine" Study: Children age $3$ interacted with a machine that "shrunk" toys. When tested $6$ to $12\,months$ later, they could only verbally recall objects if they had the vocabulary for those objects at the time of the initial visit.

  3. Sociocultural Support: The way parents "reminisce" with children matters.

     • Elaborative Style: Parents provide a rich narrative arc and ask detailed questions. Children of these parents tend to report earlier memories later in life ($12$ to $13\,years$ old).

     • Repetitive Style: Parents focus on repeating a single detail (e.g., "Remember the elephant?").

     • Training studies showed that teaching "repetitive" moms to be "elaborative" boosted child memory performance.

  4. Sense of Self: A developed self-concept (e.g., passing the Mirror Self-Recognition Task) acts as "conceptual glue" to organize events happening "to me."

  5. Verbatim vs. Gist Storage:

     • Verbatim: Rehearsing information word-for-word; requires high processing power.

     • Gist: Extracting an abstract, general summary of an event. As children age, they shift from verbatim-heavy storage to more efficient gist-based storage.

  6. Neurogenesis: The birth of new neurons in the hippocampus during infancy may "clean the slate" by disrupting existing circuits that store early memories. In humans, approximately $31\%$ of neurons emerge after the initial developmental period (a human at $20\,years$ of age is compared to a mouse at $3\,months$ in terms of neuronal emergence rates).

Questions & Discussion

• Question on Survival Mechanisms (Taste): A student mentioned reading that unfamiliar tastes are recognized as potentially poisonous as a survival method, and that we don't "taste" water so we can detect contaminants. The professor found the idea plausible as a reason for novelty hesitancy.

• Question on Early Memories without Language: A student mentioned a case of someone remembering experiences before acquiring language. The professor noted that sensory-heavy memories (smells, tactile feelings) might be stored differently than complex, temporally extended narratives, which rely heavily on language.

• Question on Anxiety/Depression and Memory: A student asked if anxiety affects childhood memory. The professor noted that while some research suggests clinical anxiety/depression can impair neutral memory, it can sometimes enhance memory for negative or traumatic events.

• Question on Memory Accuracy: A student asked how accurate infant memories are in these studies. The professor clarified that while some long-term retrospective studies have less control, specific experimental setups (like the Elaborative style training) provide more certainty, and the topic of confabulation/reliability will be covered in the next lecture.