Cognition - Module 2 - Short-term Memory PDF

Module Two made with gpt-4o Classical Research on Short-Term Memory Concept of Memory Limits Original Memory Limits: Initially, memory limits were thought to be defined by the capacity of short-term memory (STM). STM is the system responsible for holding a small amount of recently recei...

Module Two made with gpt-4o Classical Research on Short-Term Memory Concept of Memory Limits Original Memory Limits: Initially, memory limits were thought to be defined by the capacity of short-term memory (STM). STM is the system responsible for holding a small amount of recently received information. Short-Term Memory (STM) Function: STM temporarily holds information that comes from the environment. Capacity: STM has limited capacity, both in terms of: Time: How long it can retain information (short duration). Amount: How much information it can hold (limited quantity). Contrast with Long-Term Memory (LTM): Long-Term Memory (LTM): Has a much larger capacity than STM. LTM stores experiences and information accumulated over a lifetime. George Miller's Perspective on Memory Limitations George Miller, a key figure in cognitive psychology, explored and proposed ideas about the limitations of memory. He focused on how memory capacity restricts the amount of information we can hold at one time. Early Studies on Measuring Memory Limitations Various early studies aimed to measure how much information could be retained in STM. These studies helped in understanding the quantitative limits of STM. Influence of Word Meaning on STM The meaning of words plays a significant role in how many items we can store in STM. This suggests that semantic (meaning-based) factors impact the efficiency of STM storage. The Magical Number Seven George Miller's Article (1956): In his influential work, "The Magical Number Seven, Plus or Minus Two," George Miller suggested that humans have a limited capacity in short-term memory (STM). Memory Capacity: Miller proposed that people can typically hold seven items, with a range of five to nine items (hence, "7 ± 2"). Concept of a Chunk Definition of a Chunk: Miller introduced the concept of a chunk, a basic unit in STM consisting of multiple components that are strongly associated. Example of Chunks: For instance, remembering a sequence of seven numbers or letters could form seven chunks. However, if multiple adjacent digits are grouped (like in phone numbers), they can form a single chunk, which reduces the total number of chunks. Phone Number Example: The phone number 617-346-3421 could be broken into just six chunks (e.g., "617" is one chunk, "346" is another, and so on: that is, 1 + 1 + 4) Miller vs Behaviorism Behaviorism vs. Cognitive Processes: Miller's article was notable for its time because it contrasted with the then-dominant behaviorism, which focused on observable behaviors rather than internal mental processes. Early Research on Short-Term Capacity Limits (1950s–1970s) ○ Brown/Peterson and Peterson Technique: Developed by John Brown (1958, 2004) and Lloyd & Margaret Peterson (1959). Assessed how long information could be held in short-term memory, showing that material is often forgotten within a minute. Involved presenting participants with items to remember, followed by a distracting task to prevent rehearsal. Example: Participants studied three unrelated letters (e.g., CHJ), then performed a distracting task like counting backward by threes. Results showed that after a 5-second delay, participants forgot about half of the letters. This technique highlighted the fragility of short-term memory and led to many further studies. ○ Modified Brown/Peterson and Peterson Technique Preparation: Write three words on one side of six index cards and a three-digit number on the back. Task: Practice counting backward by threes from 792. Procedure: ○ Look at the words on the first card for 2 seconds. ○ Turn over the card and count backward from the three-digit number for 20 seconds. ○ Write down as many words as you can remember. Repeat: Perform the same steps with the remaining five cards. ○ Serial Position Effect Describes the U-shaped relationship between the position of a word in a list and its probability of recall. This effect is commonly used to study short-term memory. Cognitive Psychology Page 1  1. Recency Effect: The curve shows strong recall for words at the end of the list. This suggests these items are still in short-term memory at the time of recall, but they do not transfer to long-term memory. Researchers estimate the size of short-term memory to be about three to seven items using this method (Davelaar et al., 2005, 2006; R. G. Morrison, 2005). 2. Primacy Effect: There is also enhanced recall for items at the beginning of the list. These items are easier to remember because (1) they face no competition from earlier items, and (2) they are rehearsed more frequently. ○ Semantic Similarity of the Items in Short-Term Memory Explores how meaning, or semantics, can influence short-term memory retention, alongside the chunking strategy. Researchers Wickens and colleagues (1976) conducted a study using the concept of proactive interference (PI), which occurs when previously learned material interferes with the learning of new material. Key points: 1. Proactive Interference (PI): People struggle to remember new information when old information causes interference. For example, after learning several items (e.g., XCJ, IBR, TSV), a person may have difficulty recalling a new item (e.g., KRN) because the previous items interfere with the new one. 2. Release from Proactive Interference: If the category of items is shifted, such as from letters to geometric shapes, memory improves, releasing the individual from proactive interference. This change leads to performance levels similar to the initial learning phase. Wickens and colleagues demonstrated that this release could also occur when shifting semantic categories (i.e., changing the meaning of the items). 3. Experimental Design: Participants were given three trials on the Brown/Peterson and Peterson test, which involved recalling a list of three words after counting backward for 18 seconds. Wickens et al. showed that shifting the semantic category of the items led to a release from PI, improving participants' recall performance. In this study, participants saw three related words on each trial. For example, participants in the Occupations condition might begin with words like "lawyer, firefighter, and teacher" on Trial 1. On Trials 2 and 3, they saw additional occupation-related words. On Trial 4, all participants, regardless of their previous conditions, saw a list of three fruits (e.g., "orange, cherry, pineapple"). Key observations: Cognitive Psychology Page 2  Key observations: 1. Proactive Interference in the Fruits Condition (Control Group): Participants in the Fruits condition would likely experience the greatest buildup of proactive interference on Trial 4 because their short-term memory would already be filled with the names of other fruits, which would interfere with recalling the new fruit names. 2. Performance Based on Semantic Similarity: ○ Vegetables condition: These participants should perform poorly on the fruit items due to the semantic similarity between vegetables and fruits. Both are edible and plant-produced, increasing the interference. ○ Flowers or Meats condition: These participants are expected to perform better because flowers and meats only share one attribute with fruits. For instance, flowers are plant-produced but not edible, and meats are edible but not plant- produced. ○ Occupations condition: Participants in this group should perform the best because occupations do not share semantic similarities with fruits (they are neither edible nor plant-produced), thus reducing interference. 3. Results and Predictions: The study results aligned perfectly with the predictions. Semantic similarity between previously learned items and new items influenced the degree of interference in short-term memory. The closer the semantic relationship, the more interference occurred, and vice versa. 4. Implications: The findings confirm that semantic factors influence short-term memory capacity. Words previously stored in memory can interfere with the recall of new words that are semantically similar. This supports the idea that both chunking strategies and word meaning play significant roles in determining the number of items stored in short-term memo Alan Baddeley and Graham Hitch (1974) introduced the concept of working memory to replace the traditional view of short-term memory, emphasizing its role in performing complex tasks. Working memory is essential for tasks like mental arithmetic, where information must be temporarily stored and processed. Working Memory Components of the Working Memory Model: 1. Central Executive: ○ A modality-free attentional system with limited capacity. It manages cognitive tasks by directing attention and controlling the slave systems (phonological loop and visuo-spatial sketchpad). The central executive is responsible for tasks that demand significant cognitive effort. 2. Phonological Loop: ○ Processes and temporarily stores speech-based information. It helps maintain the order of words and manages subvocal articulation, where words are silently repeated. Tasks like articulatory suppression, which involves the rapid repetition of simple sounds (e.g., "the the the"), use the articulatory control process of the phonological loop, thereby preventing the system from rehearsing new verbal information. 3. Visuo-Spatial Sketchpad: ○ Specialized for visual and spatial information processing and temporary storage. It is used for tasks requiring visual or spatial manipulation, such as pressing keys in a specific order. 4. Episodic Buffer: ○ Added later to the model, the episodic buffer provides temporary storage for integrated information from the visuo-spatial sketchpad and phonological loop. It is more passive compared to the other components. Key Assumptions: If two tasks use the same component, they cannot be performed effectively together. If two tasks use different components, they can be done simultaneously with minimal interference. Application in Research: Robbins et al. (1996) examined how chess players selected moves while performing other tasks. Tasks included: ○ Repetitive tapping (control condition), ○ Random number generation (involving the central executive), ○ Pressing keys on a keypad (using the visuo-spatial sketchpad), ○ Rapid repetition of the word "see-saw" (using the phonological loop through articulatory suppression). The study revealed that selecting chess moves engaged the central executive and visuo-spatial sketchpad, but not the phonological loop. Both stronger and weaker players used the working memory system similarly. Phonological Loop In the working memory model, the phonological loop is responsible for handling and storing speech-related information. It consists of two main components: 1. Passive Phonological Store: This component is involved in the perception of speech, storing spoken words. 2. Articulatory Process: This part is linked to speech production, allowing for verbal rehearsal by repeating words to maintain them in the phonological store. Key Concepts and Evidence: - Phonological Similarity Effect: ○ The phonological similarity effect refers to the reduced ability to recall words when they sound similar. For example, recalling words like "FEE, HE, KNEE, LEE, ME, SHE" is more difficult than recalling words like "BAY, HOE, IT, ODD, SHY, UP." ○ In one study, participants’ ability to recall similar-sounding words in the correct order was 25% worse compared to dissimilar words (Larsen et al., 2000). - Complexity Beyond Phonology: ○ Research has shown that the processes behind the phonological similarity effect are more complex than originally thought. Acheson et al. (2010) discovered that semantic processes also influence this effect, indicating that it's not solely dependent on the phonological loop. ○ Schweppe et al. (2011) found that the phonological similarity effect is influenced more by acoustic similarity (how the sounds themselves are alike) than by articulatory similarity (similar movements of the mouth during speech). However, articulatory similarity had a stronger Cognitive Psychology Page 3  are alike) than by articulatory similarity (similar movements of the mouth during speech). However, articulatory similarity had a stronger effect when recall was spoken rather than written. Word-Length Effect and Phonological Loop ○ Word-Length Effect: - Baddeley et al. (1975) found that people recall more short words than long words in the correct order. This effect was observed both with visually and auditorily presented words. - When participants engaged in articulatory suppression (e.g., repeating "1 to 8"), the word-length effect disappeared for visually presented words, showing that the effect depends on verbal rehearsal. - Jacquemot et al. (2011) confirmed this with a brain-damaged patient who couldn't’t rehearse, also showing no word-length effect. ○ Doubts About Word-Length Effect: - Jalbert et al. (2011) argued the word-length effect might be due to orthographic neighbourhood size (similar words of the same length). When short and long words were matched for neighborhood size, the word-length effect disappeared, raising doubts about its validity. ○ Phonological Loop in Everyday Life: - Baddeley et al. (1988) found that a patient (PV) with an impaired phonological loop could function well in daily life but struggled with foreign language learning. PV could learn Italian word pairs but not Russian-Italian word pairs. - Papagno et al. (1991) showed that articulatory suppression slowed down foreign language learning but had little effect on learning native words. - Tullett and Inzlicht (2010) found that articulatory suppression reduced action control in demanding tasks, leading to more errors. Visuo-Spatial Sketchpad The visuo-spatial sketchpad temporarily stores and manipulates visual and spatial information. Visual processing involves remembering what, while spatial processing involves remembering where. According to Logie (1995), it consists of two components: 1. Visual Cache: Stores information about visual form and colour. 2. Inner Scribe: Processes spatial and movement information, rehearses visual cache information, and transfers it to the central executive. Findings on Separate Systems: 1. Smith and Jonides (1997) found different brain activations for visual and spatial tasks, with more right hemisphere activity for spatial tasks and more left hemisphere activity for visual tasks. 2. Zimmer (2008) showed that visual processing involves the occipital and temporal lobes, while spatial processing involves the parietal cortex. 3. Klauer and Zhao (2004) provided evidence for separate visual and spatial systems. Spatial interference disrupted spatial tasks more, and visual interference disrupted visual tasks more. Attention and Task Demand: Vergauwe et al. (2009) found that when tasks are demanding, both visual and spatial tasks require attentional resources from the central executive. In simpler tasks, interference effects are more specific to the type of task (visual or spatial). Most research indicates that the visuo-spatial sketchpad consists of somewhat separable visual and spatial components. However, it remains for the future to understand more fully how processing and information from the two components are combined and integrated. In addition, much remains unknow about interactions between the working of the visuo-spatial sketchpad and the episodic buffer. Finally, as Baddeley (2012) admitted, we know little about rehearsal processes within the visuo-spatial sketchpad. Central Executive The central executive is the most versatile and crucial component of working memory, responsible for managing attention and coordinating cognitive tasks. While it doesn't store information, it is involved in complex activities such as problem-solving and multitasking. The prefrontal cortex, particularly the dorsolateral prefrontal cortex, is strongly associated with central executive functions, although other brain areas are involved. Key Executive Processes: According to Baddeley (1996), the central executive is responsible for: 1. Focusing attention. 2. Dividing attention between two tasks. 3. Switching attention between tasks. 4. Interfacing with long-term memory. Miyake et al.'s Executive Functions (2000): Miyake et al. (2000) identified three core executive functions: 1. Inhibition Function: Suppresses dominant responses (e.g., the Stroop task). 2. Shifting Function: Switches between tasks or mental sets. 3. Updating Function: Monitors and updates working memory contents. Unity/Diversity Framework: Miyake and Friedman (2012) proposed the unity/diversity framework, suggesting that each executive function has both common elements shared across all functions and unique elements specific to each. Friedman et al. (2008) tested this framework by studying monozygotic (identical) and dizygotic (fraternal) twins. They found that genetic factors contribute to both the common and unique aspects of executive functions. Neuroimaging studies (Collette et al., 2005; Hedden and Gabrieli, 2010) showed that different prefrontal areas are activated for different executive functions, supporting the idea of both unity and diversity. Hedden and Gabrieli (2010) conducted a study examining the brain areas involved in inhibition and shifting functions. Their key findings were: 1. Several brain areas, such as the dorsolateral prefrontal cortex, anterior cingulate cortex, and basal ganglia, were strongly Cognitive Psychology Page 4  1. Several brain areas, such as the dorsolateral prefrontal cortex, anterior cingulate cortex, and basal ganglia, were strongly linked to both inhibition and shifting. 2. Some regions, like the right ventrolateral prefrontal cortex and bilateral temporo-parietal junction, were more activated during inhibition tasks than shifting tasks. 3. There was only modest evidence of brain areas more activated by shifting than inhibition. Dysexecutive Syndrome Dysexecutive syndrome is a condition where individuals with brain damage experience cognitive impairments related to the central executive (Baddeley, 1996). Symptoms include problems with response inhibition, rule generation, maintenance and shifting of sets, and information generation (Godefroy et al., 2010). Patients with this syndrome often struggle with everyday functioning, such as holding a job (Chamberlain, 2003). Stuss and Alexander (2007) argued that dysexecutive syndrome is not always a result of global damage to the frontal lobes. They identified three key executive processes linked to specific regions within the prefrontal cortex: 1. Task Setting: Planning and forming stimulus-response relationships (e.g., learning to drive or planning a wedding). 2. Monitoring: Checking task performance to avoid errors; impaired monitoring leads to variable performance. 3. Energisation: Sustained attention and concentration; deficits slow performance on tasks requiring quick responses. These processes overlap with Miyake et al.'s (2000) executive functions like inhibition and shifting. Stuss (2011) later confirmed these findings and added a fourth process, metacognition/integration, which involves coordinating and integrating what one knows and believes. This process is linked to the frontopolar prefrontal cortex (BA10). Glüscher et al. (2012) identified two separate brain networks in brain-damaged patients: 1. Cognitive Control Network: Involves the dorsolateral prefrontal cortex and anterior cingulate cortex, associated with response inhibition, conflict monitoring, and task switching. 2. Value-Based Decision-Making Network: Involves the orbitofrontal, ventromedial, and frontopolar cortex, and is connected to the limbic system, playing a role in emotional and value judgments. Central Executive Theory Limitations: 1. Task-Impurity Problem: As Miyake and Friedman (2012) highlighted, many tasks involve multiple executive processes, making it difficult to pinpoint the exact contribution of any single process. 2. Unclear Number and Nature of Executive Processes: There is still debate over what should be considered an executive process. For instance, it's uncertain whether functions like dual-task coordination, value-based decision making, and metacognition/integration should be classified as executive processes. Episodic Buffer The episodic buffer, added to Baddeley's working memory model in 2000, is a storage system that holds integrated information (chunks) in a multi-dimensional code. It acts as a bridge between the phonological loop and the visuo-spatial sketchpad, and links working memory to long-term memory and perception. Baddeley (2012) estimated its capacity to be around four chunks. Why It Was Added: The original working memory model’s components functioned too separately, and the episodic buffer helps by providing a storage system for both verbal and visual/spatial information. For example, people can recall up to 16 words in sentences, much more than what the phonological loop alone can handle, indicating the need for a buffer with chunking capacity. Relationship with Central Executive: Initially, it was believed that the central executive controlled the episodic buffer’s functions. However, more recent findings suggest that integrated information can be stored in the episodic buffer without the direct involvement of executive processes. Findings: Baddeley and Wilson (2002) found that amnesic patients with intact central executive functioning had much better immediate prose recall than those with severe executive deficits, suggesting the importance of the central executive in prose recall. However, Baddeley et al. (2009) found similar levels of impairment for recalling sentences and word lists when an additional executive task was involved, challenging the necessity of the central executive in sentence recall. Allen et al. (2012) showed that combining visual features, such as color and shape, occurs without central executive involvement, suggesting automatic integration before information enters the episodic buffer. Evaluation: The episodic buffer extends the scope of the working memory model by integrating information from both verbal and visual- spatial components. Limitations: 1. It remains unclear how exactly information from the phonological loop and visuo-spatial sketchpad is combined within the Cognitive Psychology Page 5  1. It remains unclear how exactly information from the phonological loop and visuo-spatial sketchpad is combined within the episodic buffer. 2. Research on other sensory modalities (e.g., smell, taste) and their integration into the episodic buffer is lacking. Overall Evaluation of the Working Memory Model: The working memory model is an improvement over the short-term store model by Atkinson and Shiffrin (1968), as it accounts for active processing and information storage and explains partial deficits in short-term memory observed in brain-damaged patients. The model includes verbal rehearsal as a flexible process within the phonological loop, rather than an essential mechanism. Despite its strengths, the model is oversimplified, ignoring other types of information (e.g., smell, touch) and spatial working memory differences. Additionally, more research is needed to clarify the number and nature of executive processes and the interaction between the working memory components, particularly how the episodic buffer integrates information. Simple Spans Underestimate Verbal Working Memory Capacity Introduction: The study by Pierre Barrouillet, Simon Gorin, and Valérie Camos investigates verbal working memory (WM) and how it is traditionally measured using simple span tasks. Verbal WM involves two systems: 1. Phonological loop: Stores and rehearses verbal information. 2. Central attentional system: Manages attention and additional information. Although each system has a capacity of around 4 items, individuals typically recall only 6 items in simple span tasks, not 8 as expected. The researchers hypothesized that people unknowingly underuse their WM by trying to rehearse too many items. Maxispan Procedure: To test this, they designed the maxispan procedure, where participants rehearsed only a limited number of items (to maximize the phonological loop’s capacity), leaving the remaining items for the attentional system. In three experiments, this method dramatically increased recall spans to nearly 8 items, especially when the rehearsed letters were presented auditorily and the remaining letters visually. Reappraisals of Miller's (1956) Estimate 1. Limit of Immediate Verbal Memory: ○ Miller’s original estimate of seven items applies mainly to digits. ○ Dempster (1981) found the limit is lower for letters (six) and even lower for words (five), depending on word length (Baddeley et al., 1975). 2. Challenges to the Seven-Item Limit: ○ Researchers quickly proposed that the limit is actually three or four items, not seven (Broadbent, 1975; Sperling, 1960). ○ Cowan (2001) is a key proponent of the four-item limit, arguing that this reflects the pure storage capacity of working memory (WM). 3. Conditions for Observing the Four-Item Limit: ○ To observe this capacity limit, Cowan suggests:  Preventing chunking of information.  Limiting the use of long-term memory by using repeated stimuli.  Blocking articulatory rehearsal through concurrent tasks. 4. Cowan's Model: ○ The focus of attention in WM can hold up to four chunks of information (Cowan, 1999, 2005). ○ This hypothesis is supported by research in both visuospatial WM (Luck & Vogel, 1997) and verbal WM (Chen & Cowan, 2005; Cowan et al., 2012). Explaining Why Verbal Spans Are Higher Than Four ○ Traditional Estimate of WM Capacity: ○ Cowan (2001) proposed that working memory (WM) has a pure storage capacity of about three to four chunks. However, the observed span for immediate verbal memory is typically six to seven items (Dempster, 1981). ○ Phonological Loop and Verbal Memory: ○ In Baddeley’s multicomponent model of WM, the phonological loop consists of a phonological store and an articulatory loop that reactivates decaying phonological traces through rehearsal. This explains how individuals can immediately recall verbal items they can articulate in around 2 seconds (Baddeley et al., 1975). ○ Several models, such as those by Burgess & Hitch and Botvinick & Plaut, suggest that immediate serial recall (ISR) is managed by a single system or mechanism, though some deny the separation between short-term memory and long-term memory. ○ Contributions of Multiple Systems: ○ Baddeley (2000) revised the model to include the episodic buffer, which could explain the ability to recall up to seven items by suggesting that both the phonological loop and the episodic buffer store verbal information. ○ Cowan (1988) and Zhang & Simon (1985) suggested that some chunks of information are maintained through verbal rehearsal, while others are stored nonverbally, which would explain spans higher than four items. ○ Theories of Multiple Systems in WM: ○ Logie (2011) proposed that WM capacity relies on multiple domain-specific systems that contribute jointly, while Unsworth & Engle (2007) suggested that some items are displaced into secondary memory in span tasks and retrieved through a cue-dependent process. ○ The time-based resource-sharing (TBRS) model by Barrouillet & Camos (2015) posits two maintenance mechanisms: a phonological loop for verbal rehearsal and a central system for attentional refreshing. Unanswered Questions: It remains unclear how these systems (e.g., phonological loop, episodic buffer, executive loop) jointly contribute to verbal memory Cognitive Psychology Page 6 ○ It remains unclear how these systems (e.g., phonological loop, episodic buffer, executive loop) jointly contribute to verbal memory performance. ○ A key issue is whether articulatory rehearsal is essential for verbal WM or merely an epiphenomenon, as some researchers (Lewandowsky & Oberauer, 2015) have argued. ○ Lastly, the question remains why verbal spans are often lower than predicted by the combined capacity of these systems. It Does Not Add Up: 4 + 4 = 8, Not 6 ○ Verbal STM Span for Letters: ○ Dempster (1981) found that the verbal short-term memory (STM) span for letters is about six items. ○ Combining Systems in WM: ○ The capacity of verbal working memory (WM) is often attributed to both the phonological loop and a central attentional system (e.g., the executive loop in the TBRS model or the episodic buffer in Baddeley’s model). ○ If the capacities of these two systems are combined (each holding around four items), the total should theoretically reach eight items, exceeding the typical span of six. ○ Study by Vergauwe, Camos, and Barrouillet (2014): ○ Participants performed a Brown-Peterson task where they had to remember letters while performing a parity judgment task. ○ Under articulatory suppression, response times to the parity task increased with memory load, suggesting that attention was involved in maintaining letters. ○ Without articulatory suppression, participants could maintain up to four letters without affecting response times, indicating these letters were stored in the phonological loop without attention. ○ Rehearsal Set Limit: ○ Tan and Ward (2008) found that during immediate serial recall (ISR), participants tended to rehearse up to four items, beyond which rehearsal became incomplete or unsystematic. ○ The Capacity Discrepancy: ○ If the phonological loop and central attentional system (executive loop) work together, they should support a span of eight letters, not six. ○ Interference between the systems during maintenance or recall may reduce the total capacity. ○ Possible explanations for this discrepancy: ○ People might be using their WM suboptimally in simple span tasks, attempting to rehearse too many items, leading to inefficient rehearsal beyond the capacity of the phonlogical loop. The Study 1. Hypothesis: ○ The study aimed to test the hypothesis that verbal working memory (WM) has a dual structure (phonological loop + attentional system) that remains underused in simple span tasks. ○ With specific instructions, participants should be able to use both systems effectively, leading to recall performance approaching a theoretical maximum of eight items for letters. 2. Maxispan Procedure: ○ The maxispan procedure involved participants rehearsing a limited number of items (three to five) aloud to utilize the phonological loop, while maintaining additional items in the executive loop through attentional refreshing. ○ This method aimed to prevent items from being transferred between the two systems, with rehearsed items output first, followed by items maintained in the attentional system. 3. Experiments: ○ Experiment 1: Tested the maxispan procedure with all letters presented visually. The hypothesis was that this method would result in letter spans higher than the simple span (six items). ○ Experiment 2: Tested the procedure with all letters presented auditorily (a less favorable condition). ○ Experiment 3: Used a combination where the to-be-rehearsed items were presented auditorily (to optimize the phonological loop), and the remaining items were presented visually (to facilitate encoding into the executive loop). Experiment 1: 1. Aim of Experiment: ○ To test whether the maxispan procedure improves letter span recall compared to the simple span procedure. 2. Method: ○ Participants: 40 students from the University of Geneva, divided into two groups (maxispan vs. simple span). ○ Procedure: Letters were visually presented, with blue letters rehearsed aloud and black letters recalled mentally in the maxispan group. ○ Design: 2x3x6 mixed repeated-measures design varying the number of blue and black letters. 3. Results: ○ Maxispan group had significantly higher spans (7.30 vs. 6.10). ○ Blue letters benefited from rehearsal in the maxispan group, unaffected by the number of black letters. ○ Black letter recall was also better in the maxispan group, though less so with five blue letters rehearsed. 4. Conclusion: ○ The maxispan procedure directed items into separate memory systems, optimizing recall performance for both blue and black letters Experiment 2 1. Aim: This experiment replicated the first but with auditory presentation of letters rather than visual. The goal was to confirm the higher recall spans observed in the maxispan procedure. 2. Method: Cognitive Psychology Page 7  2. Method: Participants: 40 participants from the University of Geneva were recruited (20 per group: maxispan and simple span). Procedure: Auditory letters were presented at a rate of one every 2,000 ms. Visual cues (colored squares) indicated whether the letter should be rehearsed. Materials: Auditory letters recorded and presented through loudspeakers. 3. Results: Span Measures: ○ Maxispan procedure led to better spans than simple span (μ = 6.52 vs. μ = 5.82, BF10 = 5.74, Cohen's d = 0.88). ○ Strong evidence for interaction between the number of blue letters and the procedure. For the maxispan group, increasing the number of blue letters to rehearse resulted in higher spans, particularly between three and four blue letters. Serial Recall Accuracy: ○ Blue Letters: The recall of blue letters was higher in the maxispan group (μ =.89) compared to the simple span group (μ =.71), though recall accuracy decreased as the number of black letters increased. ○ Black Letters: Black letter recall also performed better in the maxispan group (μ =.56) than in the simple span group (μ =.44), with a decrease as more blue letters were rehearsed. Serial Position Curves: ○ Both groups showed a strong primacy effect and a small recency effect. Blue letters in the maxispan group were largely unaffected by serial position for three or four letters, but a serial position effect appeared with five blue letters. ○ The recency effect was more pronounced in this experiment due to the auditory presentation. 4. Discussion: The experiment confirmed the results of Experiment 1, with higher spans in the maxispan condition, though spans were overall lower due to the auditory presentation. The recall of black letters was more affected by auditory presentation in the maxispan group, but the segregation of storage systems (phonological loop and attentional system) in the maxispan procedure still led to better performance than the simple span group. Auditory presentation was detrimental to both procedures but still allowed for improved performance in the maxispan procedure due to effective use of verbal rehearsal for blue letters. This experiment's findings supported the bipartite structure of verbal working memory and the effectiveness of the maxispan procedure in leveraging these systems for enhanced recall. Experiment 3: 1. Aim: ○ To optimize the use of the phonological and executive loops for better memory span performance. 2. Method: ○ Participants: 40 University of Geneva students divided into two groups (maxispan vs. simple span). ○ Procedure: Blue letters were presented auditorily, black letters visually for multimodal encoding. 3. Results: ○ The maxispan procedure led to significantly higher spans (7.73 vs. 6.37). ○ Better recall accuracy was observed for both blue and black letters in the maxispan group. 4. Conclusion: ○ The maxispan method enhanced recall by optimizing the use of different memory systems. General Discussion Aim and Findings: ○ The study tested a dual-system model of verbal working memory (WM), which suggests two independent systems: a phonological loop and an executive/attentional system. The maxispan procedure optimized the use of these systems, leading to improved letter spans compared to the traditional simple span task. Key Theoretical Implications: ○ Dual-System Approach: Evidence supported the hypothesis that verbal WM relies on two systems. The phonological loop is used for rehearsing items, while the executive system maintains additional items via attentional refreshing. ○ Performance Increase: The maxispan procedure led to spans closer to the theoretical maximum of eight items, especially when letters were presented in an optimal auditory-visual combination, reducing interference between the two systems. Support for Independence of Systems: ○ Serial Position Curves: Rehearsed items showed flat serial position curves (indicating nearly perfect recall), while non-rehearsed items displayed primacy effects, supporting the idea of two separate systems. ○ Resilience to Interference: Rehearsed letters in the maxispan procedure were unaffected by the number of additional items, unlike in the simple span task, further indicating separate storage systems. Effectiveness of Verbal Rehearsal: ○ Contrary to previous claims, verbal rehearsal was shown to be an efficient method of maintaining items in WM. This finding aligns with prior research on cumulative rehearsal in free recall tasks. Capacity of Systems: ○ While the phonological loop can hold up to four items, adding more items begins to impact the executive system. This suggests that verbal rehearsal is effective but limited by the phonological loop's capacity. Attention-Based Maintenance: ○ Black letters (encoded under articulatory suppression) were maintained in the attentional system, supporting models like the time-based resource-sharing (TBRS) model. However, the number of items maintained by attention never exceeded four, the hypothesized capacity of the focus of attention. Evidence of Two Systems: Both behavioral and neurological evidence support the dual-system model. Brain areas related to speech production are Cognitive Psychology Page 8  ○ Both behavioral and neurological evidence support the dual-system model. Brain areas related to speech production are activated during verbal rehearsal, while different regions (e.g., prefrontal cortex) are involved in attentional refreshing. Alternative Hypotheses: ○ The study ruled out the possibility that improved performance in the maxispan condition was due to chunking or subjective grouping strategies. Serial position curves and transposition error patterns in the maxispan condition indicated the involvement of two distinct systems, not grouping effects. Neurological Evidence: ○ Neurological findings show distinct brain activations for articulatory rehearsal and attentional refreshing, supporting the idea of two separate systems in verbal WM. Nature of Different Systems Dual-System Structure: The maxispan procedure indicates two separate systems in verbal working memory (WM): a phonological loop and an executive loop. These systems manage up to four items each, with the phonological loop relying on rehearsal and the executive loop on attentional maintenance. Alternative Models: ○ Unsworth & Engle’s model of primary and secondary memory doesn't fit, as black letters in the maxispan procedure showed active recall with primacy effects, not passive maintenance with recency effects. ○ Sensory memory was also ruled out since the black letters' recall patterns didn’t match sensory memory effects. Primacy Effect: The strong primacy effects in recalling black letters suggest active maintenance through attention, supporting the involvement of the executive loop. Conclusion ○ Nature of STM Spans: STM spans are not limited by a single short-term buffer but are influenced by two distinct storage systems: the articulatory loop (holding motor programs) and the attentional central system (maintaining symbolic representations). This complexity suggests that seemingly simple tasks, like recalling a list, involve multiple mental processes. ○ Complexity of Measuring STM: Simple spans, like the digit span task, do not solely reflect the capacity of one cognitive structure but rather the interaction between different systems. This makes measuring STM capacity more complex than previously assumed. ○ Maxispan vs. Simple Span Tasks: While the maxispan procedure reveals deeper insights into STM, it does not replace the traditional simple span tasks, which have been useful in assessments for over a century. However, understanding what these tasks measure enhances their diagnostic and prognostic power. Cognitive Psychology Page 9