practice exam q's Flashcards
Which acquired reading disorder is characterized by errors of the type ciGAR read as CIGar (with stress on the first syllable instead of on the second) and so-called ‘regularization’ errors in which the word ‘said’, for instance, would be read as ‘sade’, rhyming with ‘maid’, ‘laid’ and ‘raid’? How are these errors typically explained by the Dual Route Cascaded model (Coltheart et al. 2001)?
This is surface dyslexia (Marshall & Newcombe, 1973). According to the dual route model, both types of errors reflect a damage to the lexical route. In normal circumstances the lexical route allows the reader to retrieve both pronunciation and meaning by simply locating the word in memory. Because cigar and said are exceptions –most English words are stressed on the first syllable and most words ending by the letters AID are pronounced ‘ade’ as in ‘maid’– their correct pronunciation can only be retrieved from word-specific knowledge, that is by the lexical route. Given that surface dyslexics tend to read irregular words (like ‘cigar’ and ‘said’) following the rule rather than the exception, one must conclude that the lexical route is faulty.
In the Dual Route Cascaded model of reading (Coltheart et al. 2001), how does the non-lexical route give you the pronunciation for a given letter string?
By segmenting the letter string into individual graphemes, that is, letters or groups of letters which by experience the reader knows they map onto individual sounds of the language, and by assembling those sounds into a phonological form that can then be passed to the articulators.
In their effort to map predictions of computational models of reading onto patterns of brain activation, Taylor et al. (2012) invoke the notions of engagement and effort. What do these notions refer to in this context?
Engagement refers to the likelihood of having a component in a cognitive model deal with a particular type of stimuli. For example, known words should engage semantic memory, whereas made-up words that do not resemble or sound like known words should not. Effort, in contrast, refers to the ease with which a stimulus is processed by a dedicated component, once this component is engaged. For example, the lexical route should produce a bigger effort in order to process uncommon words (for which it has only faint memories) compared to frequent words (for which it has stronger memories). Thus, engagement dictates whether activity should be seen in a brain region. In where its level should be directly proportional to how much processing effort has to be produced.
What is the link between the shape of forgetting curves and the notion of memory consolidation?
The mathematical function that best describes the forgetting curve is one where the rate of memory loss gets smaller and smaller over time. The fact that less and less is forgotten is exactly what the notion of memory consolidation predicts: if time is required for the stabilization of information in the system, performance should initially drop abruptly soon after encoding, to then approach an asymptote as time goes by.
What are phonemes? Illustrate your answer with an example of your choice
Phonemes represent the smallest parts of speech in a language, that distinguish between one word and another. /m/ and /b/ must be two distinct phonemes in English, because ‘mat’ and ‘bat’ are two different words, each with their specific meaning.
What effect does perceptual load have on attentional selection?
There is a longstanding debate over whether attention operates at an early or late stage in processing, i.e. whether unattended information is filtered out or is subject to more elaborate processing. Nilli Lavie provided a potential resolution to this problem by demonstrating that the stage at which attention operates is intimately dependent on the perceptual characteristics of the task that the subject is performing. When perceptual load is high, participants are less vulnerable to distraction (attention operates at an early stage) whereas when perceptual load is low, participants are more vulnerable to distraction (attention operates at a late stage).
What role do the basal ganglia play in executive function?
The basal ganglia (including the putamen, caudate, ventral striatum, globus pallidus) operate as part of a set of neuroanatomical frontostriatal loops with strong connections to the prefrontal cortex (PFC). Whilst different basal ganglia regions are connected to different PRC regions and have been hypothesized to play different functions, the overall function of these areas seems to be to act as a ‘gatekeeper’ for the entrance of new goal representations into the PFC, mediated via dopaminergic signalling. Much of the original evidence for this role came from studies of Parkinson’s Disease, which demonstrated impairments in these patients in tasks requiring cognitive flexibility, for example task switching and attentional control (Cools et al., 2001), which were supported by later neuroimaging studies demonstrating modulation of striatal activation by dopaminergic drugs during cognitive flexibility (e.g. Dodds et al., 2008).
Critically evaluate the ‘standard model’ of the role of the prefrontal cortex in working memory
The standard model of the role of the prefrontal cortex (PFC) in working memory is the hypothesis that the PFC holds online a neuronal representation (a ‘template’) of to-be-remembered information during the delay period of working memory tasks. There is now substantial evidence that this model is incorrect – for example, studies employing Multi Voxel Pattern Analysis (MVPA) of fMRI data have failed to decode information about the category or identity of remembered information from patterns of activation in the PFC during a working memory task (e.g. Riggall & Postle, 2012), suggesting that this information must be stored elsewhere. Current theories posit a distributed system in which item-specific information is stored in posterior sensory-specific regions whilst the PFC carries out various operations on that information depending on current task demands.
Are faces special?
There is both behavioural and neuroscientific evidence that faces are processed and recognized differently from other common objects. Behaviourally, a study by Tanaka & Farah (1993) showed that people were better at identifying whole faces than individual face parts, whereas this difference did not exist for houses, suggesting that faces, unlike other objects, are processed holistically. Neuroscientifically, there is strong evidence from patients with selective deficits in face recognition after brain lesions, and fMRI studies showing selective activation to faces in the fusiform face area, for a module in the visual system of the brain that is dedicated to processing human faces, although this evidence has been challenged by fMRI studies showing that neuronal representations of faces may be more distributed across ventral visual cortex.
What does visual extinction tell us about attention?
In visual extinction, patients with a brain lesion in one hemisphere can see an individual stimulus in one side of space (or one side of a stimulus) but have difficulty responding to a stimulus on the contralesional side when it is paired with an ipsilesional stimulus. This suggests that visual attention operates as a process of biased competition; stimuli in the external world compete for limited attentional resources and when one hemisphere is damaged, stimuli processed by the other hemisphere gain a competitive advantage. However, studies such as the one by Vuilleumier (2001) showed that extinguished stimuli with emotional valence, such as spiders, can be processed in the absence of awareness, suggesting that attentional selection can operate at a relatively late stage in the sensory processing stream.
