Thursday, January 23, 2014

Individual differences in processing speed mediate a relationship between working memory and children's classroom behaviour

Jarrold, C., Mackett, N., Hall, D. (2013). Individual differences in processing speed mediate a relationship between working memory and children's classroom behaviour. Learning and individual Differences. /10.1016/ j.lindif.2013.10.016.

Studies show that poor working memory capacity is associated with attention problems in a classroom setting. In this study, Jarrold and colleagues examine the relationship between working memory and classroom behaviour in more detail by examining three components of working memory: domain-specific storage capacity, domain-general processing efficiency, and a supervisory/coordinating function (Bayliss, Jarrold, Gunn, & Baddeley, 2003). The aim of this study was to understand which of these key factors of working memory drive the relation between working memory performance and teachers’ ratings of classroom behaviour.

In this study, 47 children in grades 1 and 2 completed measures of short-term storage capacity only, processing efficiency only, or working memory incorporating both storage and processing. Teachers completed a classroom behaviour rating scale for each child. Results revealed that processing speed was the only significant predictor of individual behaviour in the classroom, and in particular, inattention.

The authors suggested that speed of processing may have a relatively general effect on individual behaviour, and this is most easily observed in terms of problems of attention.

Blogger: Areej Balilah.

Monday, January 13, 2014

The three principal functional units in the working brain: An introduction to neuropsychology

Luria, A.R. (1973). The three principal functional units in the working brain: An introduction to neuropsychology (p. 43-101). New York, NY: Basic Books Inc.

In this classic text, Luria describes three principal functional units of the brain whose participation is necessary for mental activity. Each unit has a hierarchical structure consisting of at least three cortical zones: the primary area receiving or sending impulses to the periphery, the secondary area where information is processed or programmed, and the tertiary area involving overlapping zones.

The first functional unit is for regulating tone and waking and mental states and involves the reticular activating formation. This system maintains the optimal level of cortical tone for engaging in organized, goal-directed activity. Processes of excitation obey a law of strength whereby stronger responses are evoked by strong stimuli. Excitation in this system spreads gradually leading to modulation of the entire nervous system. Activation may occur in response to metabolic responses of the organism (e.g., feelings of hunger), stimuli from the outside word leading to an orienting reflex, or to intentions and plans.

The second functional unit is for receiving, analyzing, and storing information, and involves the lateral regions of the neocortex including the visual, auditory, and general sensory regions. The systems of this unit analyze very large numbers of very small component elements, and respond to dynamic functional structures of these stimuli. This system has high modal specificity with component parts adapted to visual, auditory, vestibular, or general sensory information. Associative neurons occurring in the secondary area have less modal specificity, and allow for responding to complex patterns. The tertiary area is a zone of overlapping cortical end of the various analyzers, and allows for the integration of excitation arriving from difference analyzers.

The third functional unit is for programming, regulation, and verification of activity, and largely involves the frontal lobes. This system allows for the creation of intentions, plans, and programming of action, regulating of behaviour, and verifying conscious activity.

The neuropsychological evidence for these three integrated systems provides an evidence base for clinical approaches that consider both the more modality-specific tasks of auditory, phonological, and linguistic learning, and the domain-general executive functions supporting planning and regulating behaviour.

Blogger: Lisa Archibald

Monday, December 2, 2013

Executive Functions: Inhibitory Control, Working Memory, and Cognitive Flexibility

Diamond, A. (2013). Executive Functions. Annual Review of Psychology, 64, 135–168.

Diamond refers to executive functions (EFs) as a “family” of mental processes necessary for concentrating or paying attention. In this review paper, Diamond walks through three core EFs: inhibitory control, working memory, and cognitive flexibility.

Inhibitory control is our ability to choose what to focus on while suppressing distractors or impulsive behaviours. Aspects include using self-control, staying on task, resisting temptation, and delaying gratification. These aspects can be assessed using a variety of behavioural measures. One example of a delayed gratification test is the marshmallow test, in which children are asked to choose between receiving one marshmallow now or two marshmallows if they wait.

Working memory, the ability to manipulate verbal or nonverbal material while holding it in mind, tends to work closely with inhibitory control. For example, working memory supports inhibitory control by holding the current goal in mind, which makes it easier to stay on task. Similarly, inhibitory control can support working memory by suppressing irrelevant ideas and decluttering our mental workspace. This overlap can make it difficult to separate working memory and inhibitory control, although some research with older adults is showing that the ability to suppress unwanted ideas or actions (i.e., inhibitory control) is separate from the ability to activate appropriate ideas or actions (i.e., working memory). Diamond notes the difficulty in assessing working memory, arguing that many tasks assess only the storage of information, whereas others go beyond the scope of working memory and require more subcomponents of EFs.

Cognitive flexibility allows for mental adaptability and versatility, such as thinking “outside the box,” seeing something from a different perspective, or switching tasks or priorities. A task commonly used to assess cognitive flexibility is a card sorting task. For this activity, subjects are given cards with images that could be sorted according to a few different features (e.g., colour of object , shape of object, background colour) and asked to sort them. Subjects may be asked to sort the cards based on trial-by-trial feedback they receive, or they may be asked to sort them according to one dimension first, and another later on.

Diamond notes that EFs are highly affected by stressors such as depressed mood, sleep deprivation, or insufficient exercise. She concludes by outlining five principles of effective intervention for EF: 1) those with lowest EF will benefit the most; 2) extent of transfer depends on the type of intervention; 3) demands on EF need to continually increase; 4) repetition is essential; 5) biggest differences between trial groups and control groups are seen on the most demanding tasks.

Blogger: Laura Pauls is a PhD student in Speech & Language Science, researching children with language impairment and/or working memory impairment.

Tuesday, November 12, 2013

Sentence processing: The role of memory and expectations in understanding relative clauses

Levy, R., Fedorenko, E., & Gibson, E. (2013). The syntactic complexity of Russian relative clauses. Journal of Memory and Language, 69, 461-495.

Human language is unique amongst communication systems because of its expressivity: We can hear a sentence we have never heard before and understand its meaning. But how does this happen? We do not have the memory resources to pursue every possible interpretation of a sentence, so there must be some sort of cognitive constraint that guides our understanding. Possible cognitive constraints have been investigated by examining how long it takes for people to understand or read sentences that present some confusion, that is, syntactic ambiguity resolution.

Research in processing relative clauses is important in understanding syntactic ambiguity resolution because these are one of the most complex sentence forms we encounter, and they offer an avenue to explore language’s rich expressive capacity. There are two types of relative clauses examined in this paper:

1)   Subject-extracted relative clause
The reporter who attacked the senator hoped for a story
            subject                 relative clause verb        object

2)   Object-extracted relative clause
The reporter who the senator attacked hoped for a story
                 object                                      subject  relative clause verb

The finding is that object relative clause sentences are more difficult to process than subject relative clause sentences. The authors distinguish between two theories that explain this difference in processing: Memory Based Theories and Expectation Based Theories. Memory Based Theories state that the comprehender is actively storing, integrating, and retrieving incoming information from the sentence in an online fashion. In these theories, the more material that needs to be processed, the more overloaded the memory system gets and the higher the processing load. Based on this theory, sentence 2 is harder to process because you need to hold more information in memory before you get to the verb attacked, which is the point where the meaning of the sentence becomes clear.
Expectation Based Theories assume that your previous language experience and semantic content shapes your sentence processing abilities. In fact, for Expectation Based Theories, greater semantic information (more words) in the sentence helps sharpen your expectations and guides your processing, whereas Memory Based Theories would predict that this impairs in processing. Based on this theory, sentence 2 is harder to process because it follows an Object-Subject-Word order. We are used to hearing Subject-Verb-Object orders in English, so this violates our expectations.

Even though the theories were difficult to disentangle in this paper, there are two interesting ideas in this paper: Memory limits may constrain language processing, and language processing may be limited by a lack of language knowledge. Considering which of these resources may be impacting language processing may help to understand a particular individual’s language functioning.

Blogger: Nicolette Noonan