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Definition and Research Focus

• Memory refers to the processes involved in retaining, retrieving, and using information about stimuli, images, events, ideas, and skills after the original information is no longer present.
• Memory researchers study issues such as the number of memory systems, how each type of memory functions, factors that harm or enhance memory, and how memory changes with age.

Atkinson and Shiffrin’s Modal Model of Memory

• Atkinson and Shiffrin (1968) suggested we have three memory systems: Sensory Memory (SM), Short-Term Memory (STM), and Long-Term Memory (LTM).
• Sensory information first enters Sensory Memory and is stored for less than a few seconds.
• Attention sends it to Short-Term Memory, which is a limited capacity temporary store.
• Rehearsal keeps information alive in STM, and when rehearsal stops, it is quickly forgotten or transferred to LTM.
• Problems with the Modal Model: oversimplification, each system has subsystems with unique functions.

Verbal Short-Term Memory (STM)

• Definition: the ability to hold in mind, in an active, highly available state, a small amount of information.
• How it is studied: participants study a series of stimuli for a couple of seconds each and then immediately recall them.
• Prior to the 1970’s, researchers primarily studied recall of verbal (language-based) stimuli such as letters and numbers (Verbal STM).

Verbal STM Capacity

• Jacobs (1887) conducted an early STM study using the digit span test.
• Participants could repeat 7.3 letters and 9.3 numerals on average, suggesting people can hold 7 – 9 items in verbal STM.
• The digit span test is still the main method of studying Verbal STM today.

The Phonological Loop and The Visuo-Spatial Sketchpad

• The phonological loop is responsible for the temporary storage and rehearsal of verbal information.
• The visuo-spatial sketchpad is responsible for the temporary storage and rehearsal of visual and spatial information.

The Central Executive and Episodic Buffer

• The central executive is responsible for attention, decision-making, and error detection.
• The episodic buffer integrates information from different sources, such as the phonological loop and the visuo-spatial sketchpad.

Increasing Verbal STM Capacity

• Miller (1956) showed that LTM can be used to boost Verbal STM’s capacity by grouping information into meaningful chunks.
• Ericsson et al. (1980) examined whether we can increase our Verbal STM capacity through practice.
• S.F. practiced the digit span test and increased his digit span from 7 to 79.

Verbal STM Storage Duration

• Information is retained in Verbal STM while we are thinking about it (rehearsal).
• When we stop thinking about it (rehearsal stops), it quickly leaves STM.
• Peterson and Peterson (1959) found that without rehearsal, forgetting starts immediately and almost all items are forgotten within 18 seconds.

Working Memory

• Development 1: Cognitive Neuropsychological Research identified a double-dissociation between Verbal STM and Visuo-Spatial STM, suggesting STM has at least two systems.
• Development 2: STM shown to underpin abilities such as reading, problem-solving, and conversations (Baddeley and Hitch, 1974).
• The Working Memory Model, proposed by Baddeley and Hitch (1974), has several systems and emphasizes STM’s role in underpinning cognitive tasks.

What is Memory?

• Atkinson and Shiffrin (1969) proposed the Modal Model of Memory, which saw Short-Term Memory (STM) as a unitary system for temporarily storing small amounts of information.

Development of the Working Memory Model

• In the early 1970s, brain lesion research showed that Verbal STM and Visuo-Spatial STM are distinct systems, and STM underpins many cognitive abilities.
• Baddeley and Hitch (1974) proposed the Working Memory Model, which emphasized STM's role in underpinning cognitive tasks.

Defining Working Memory

• Baddeley and Hitch (1974) defined Working Memory (WM) as "a limited-capacity system for temporary storage and manipulation of information for complex tasks such as comprehension, learning, and reasoning."

The Working Memory Model

• The model has four systems: Phonological Loop, Visuo-Spatial Sketchpad, Central Executive, and Episodic Buffer.
• Phonological Loop: temporarily stores language/sound-based information, with two sub-systems: Phonological Store and Articulatory Control Process.
• Visuo-Spatial Sketchpad: temporarily stores images/spatial location information, with two sub-systems: Visual Cache and Inner Scribe.
• Central Executive: an attention system that focuses attention, divides attention between tasks, and switches attention between tasks.
• Episodic Buffer: integrates information from Phonological Loop, Visuo-Spatial Sketchpad, and Long-Term Memory.

Phonological Loop

• The Phonological Store stores information in a phonological (sound-based) code or format.
• The Articulatory Control Process converts written words into a phonological code using subvocal articulation (rehearsal) before sending them to the Phonological Store.

Testing the Phonological Loop

• Evidence from studies by Baddeley (1990) and Conrad (1964) supports the idea that written and spoken letters/words are stored in phonological codes.

The Phonological Loop and Language

• The Phonological Loop is important for language acquisition, as it enables us to temporarily store and repeat unfamiliar sound patterns (new words).

Visuo-Spatial Sketchpad

• The Visuo-Spatial Sketchpad has two systems: Visual Cache (stores visual information about object shapes, patterns, and colors) and Inner Scribe (stores spatial information about object locations and movement).
• The Visuo-Spatial Sketchpad is important for tasks such as learning new routes and visual search.

The Central Executive

• The Central Executive is an attention system that focuses attention, divides attention between tasks, and switches attention between tasks.

The Episodic Buffer

• The Episodic Buffer temporarily stores integrated information from the Phonological Loop, Visuo-Spatial Sketchpad, and Long-Term Memory.

Importance of Working Memory

• Working Memory is important for everyday abilities such as comprehension, learning, and reasoning.

Strengths and Limitations of the Working Memory Model

• The model explains findings from a wide range of research topics, including language development, counting, and problem-solving.
• The model is oversimplified, ignoring some kinds of information, and more research is needed on the interactions among the components.