Semantic Knowledge in Patient HM

5 Key excerpts on "Semantic Knowledge in Patient HM"

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  eBook - PDF

  Language and Memory

  Aspects of Knowledge Representation

  • Hanna Pishwa(Author)
  • 2011(Publication Date)
  • De Gruyter Mouton

    (Publisher)

  Rather than using the container metaphor, we should say that semantic knowledge is knowledge of such cognitive representations. Activated by aural or visual (including linguistic) signals, they can, e.g., be applied to a piece of text when understanding it (as coherent). Because it is knowledge about the world, which we have acquired through experience and learning in a life-long process, semantic knowledge also enables us - to relate categories and concepts to other categories and concepts, which may be more specific or more general, similar or different etc.; such relations have been variously described in linguistics as relations of reference, hyponymy, synonymy, meronymy etc.; - to arrange categories and concepts in a temporal, spatial, causal etc. order, i.e., as anterior or posterior, as close or remote, as cause and effect, and to make projections from conceptual domain to conceptual domain; such arrangements and projections have been variously described in linguistics as types of deixis, types of iconicity (diagrammatic, metaphoric, metonymic) etc.; - to draw conclusions, make predictions, maximize information (in a gestalt creating sense), variously described in linguistics as entailment, presupposition, implicature, frame and script etc.. To take a few examples from text (1), as a reader I can say that I know 'what and where Pennsylvania is', 'who Kerry and Bush are and that they ran for presidency', 'that Bush's friends are people, not pets', 'that the writer believes that hating gays and not wanting abortion are not important issues', 'that the lie works because you keep speaking it', 'that humans are mortal', and much more. It is generally agreed that we can best conceive of semantic knowledge as knowledge that is structured, flexible and heterogeneous. In artificial intelligence (Minsky), sociology (Goffman), psychology and linguistics, numerous descriptive constructs have been established to capture the con-cept of (a piece of) structured knowledge.

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  The Psychology of Cognition

  An Introduction to Cognitive Neuroscience

  • Durk Talsma(Author)
  • 2023(Publication Date)
  • Routledge

    (Publisher)

  Episodic memory is constructive. That is, memories are reconstructed from the individual memory traces when they are retrieved. The functions involved in this reconstruction can also be used for imagining future scenarios. In addition, these reconstructive processes result in people becoming sensitive to false memories. This sensitivity appears to increase with age. The hippocampus in particular appears to be involved in these reconstructive processes.

  Semantic memory is formed by a network of interconnected concepts, where the activation of specific concepts results in the activation of related concepts through the principles of spreading activation. Originally, concepts were assumed to be organised in a hierarchical way. Although the original models aiming to describe this hierarchy generated predictions that were inconsistent with the empirical evidence, later results indicate that there is indeed a hierarchical organisation of concepts. Here, a basic level, a subordinate level, and a superordinate level can be distinguished. Although most concepts are named at the subordinate level, this is not always the case, for example in the case of experts, who often describe objects in the domain of their expertise at the subordinate level.

  Initially, it was believed that concepts were represented in semantic memory in an abstract and amodal manner. This idea has been surpassed by an increasing number of studies that have shown that perceptual and motor codes are also represented in semantic memory. For this reason, it is currently more common to think of semantic memory in terms of a hub-and-spoke model.

  A final organisational principle that we can identify in semantic memory consists of schemas and scripts. These knowledge structures represent the underlying organisation of concepts. Scripts describe a sequence of actions. Neuropsychological studies indicate a double dissociation between patients who have a deficiency in the representation of semantic concepts and patients who have a deficiency in the sequencing of actions. Scripts often consist of clusters of action patterns.

  Non-declarative memory is traditionally characterised by all processes that are not accessible to consciousness. These include habituation and sensitisation, priming, classical conditioning, and procedural learning. This distinction was initially identified on the basis of studies with amnesia patients. However, more recent neuroimaging studies imply that the classical distinction is no longer tenable. There does not appear to be a strict separation between implicit and explicit memory, and the involvement of the underlying neural mechanisms also depends on specific task conditions.

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  Cases of Amnesia

  Contributions to Understanding Memory and the Brain

  • Sarah E. MacPherson, Sergio Della Sala, Sarah E. MacPherson, Sergio Della Sala(Authors)
  • 2019(Publication Date)
  • Routledge

    (Publisher)

  They were relevant for a number of reasons. On the one hand, the patients’ severe yet relatively circumscribed disorder of semantic memory provided a validation of the theoretical distinction between semantic and episodic memory, which had been advanced two decades earlier (Tulving, 1972, 1983). On the other hand, these cases provided challenges to existing accounts of semantic memory. In Tulving’s original formulation, semantic memory was defined as information that is i) acquired early in life, ii) culturally shared and iii) not tied to a particular temporal or spatial context. The implication was that semantic knowledge of words and objects, once acquired, represents an essentially stable knowledge base that is independent of autobiographical experience. Language-based models of semantic memory, construed in terms of a hierarchical network (Collins & Quillian, 1969) or a set of defining and characteristic features (Smith, Shoben & Ripps, 1974), also supposed a relatively static storehouse of concepts, divorced from experience. Yet, the findings in KE and WM suggested a more complex and dynamic interplay between semantic memory and personal experience.

  To a certain extent, there is now much greater appreciation of the interdependence between aspects of memory. The finding of an effect of personal experience on knowledge has been replicated by independent studies of semantic dementia (Péron et al., 2015; Westmacott, Leach, Freedman & Moscovitch, 2004). Péron et al. controlled for frequency of encounter, reinforcing our own findings that the experiential effect is a direct effect that is not equivalent to cumulative frequency of occurrence or overall familiarity. Other studies have reported an impact of semantic memory impairment on autobiographical and episodic memories (Graham, Simons, Pratt, Patterson & Hodges, 2000; Irish, Addis, Hodges & Piguet, 2012; Maguire, Kumaran, Hassabis & Kopelman, 2010; Westmacott et al., 2001) and conversely an impact of episodic memory impairment on semantic memory (Greenberg & Verfaellie, 2010).

  Nevertheless, theories of semantic memory still pay scant attention to the interrelationship. There is nowadays a general consensus that semantic memory involves distributed brain networks. There is evidence that the brain regions involved in representing sensory and motor properties of object concepts (colour, taste, form, movement etc) correspond to those involved in sensory perception and action (Martin, 2007; Pulvermüller, 2012). Thus, object concepts are grounded in and emerge from activity within property-based brain regions—although whether there need also be an amodal level of representation, which abstracts away from modality-specific attributes, remains an area of contention (Patterson, Nestor & Rogers, 2007). I find these studies impressive and the data arising from them hugely illuminating. They are crucial for our understanding of how the brain represents knowledge about objects. Yet, I think KE and WM serve as a reminder that semantic memory is more than an assemblage of properties of objects. It encompasses all that we know and how we function in and interact with the wider world. To my mind, this broader conception of semantic memory is the major challenge for semantic memory theorists.

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  Cognition

  • Thomas A. Farmer, Margaret W. Matlin(Authors)
  • 2023(Publication Date)
  • Wiley

    (Publisher)

  Psychologists, how- ever, use the term semantic memory in a much broader sense (McNamara & Holbrook, 2003). For exam- ple, semantic memory includes general knowledge (e.g., “Martin Luther King, Jr., was born in Atlanta, Georgia”). It also includes lexical or language knowledge (e.g., “The word justice is related to the word equality”). In addition, semantic memory includes conceptual knowledge (e.g., “A square has four sides”). Semantic memory influences most of our cognitive activities. For instance, semantic memory helps us determine locations, read sentences, solve problems, and make decisions. Categories and concepts are essential components of semantic memory. In fact, you need to divide up the world into categories to make sense of your knowledge (Davis & Love, 2010). A category is a set of objects that belong together. Your cognitive system considers these objects to be at least partly equivalent (Barsalou, 2009; Chin-Parker & Ross, 2004; Markman & Ross, 2003). For example, the category called “fruit” represents a certain category of food items. A category tells us something useful about their mem- bers (Close et al., 2010; Murphy, 2010; Ross & Tidwell, 2010). For example, suppose that you hear some- one say, “Rambutan is a fruit.” You conclude that you should probably eat it in a salad or a dessert, instead of frying it with onions and freshly ground pepper. Psychologists use the term concept to refer to your mental representations of a category (Murphy, 2010; Rips et al., 2012; Wisniewski, 2002). In other words, the physical category called “fruit” is stored as a mental representation distributed throughout your cerebral cortex. For instance, you have a concept of “fruit,” which refers to your mental representation of the objects in that category. Incidentally, I will follow the tradition in cognitive psychology of using italics for the actual word names (e.g., justice) and quota- tion marks for categories and concepts (e.g., “fruit”).

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  No longer available |Learn more

  Stevens' Handbook of Experimental Psychology and Cognitive Neuroscience, Language and Thought

  • (Author)
  • 2018(Publication Date)
  • Wiley

    (Publisher)

  Evidence from individuals with severe episodic memory deficits can help address the question of whether a functioning episodic memory system is necessary to acquire new semantic knowledge. For instance, research on the famous amnesic patient H. M. revealed that after the surgery that led to his amnesia, he acquired some new semantic knowledge (e.g., for words that came into common use after his surgery cf. Gabrieli, Cohen, & Corkin, 1988 and O'Kane et al., 2004). Two other individuals who became amnesic as adults have also exhibited some, albeit extremely limited, new semantic knowledge after the illnesses that led to their amnesia (Bayley, O'Reilly, Curran, & Squire, 2008; Bayley & Squire, 2005). Furthermore, individuals who have had amnesia since early childhood appear to have relatively intact semantic knowledge, despite the fact that they had little time to acquire semantic knowledge when their episodic system was intact (Bindschaedler, Peter-Favre, Maeder, Hirsbrunner, & Clarke, 2011; Gardiner, Brandt, Baddeley, Vargha-Khadem, & Mishkin, 2008; Vargha-Khadem et al., 1997). Although such evidence seems to suggest that semantic knowledge can be acquired without an intact episodic memory system, it is worth noting that semantic knowledge acquisition in these amnesic patients is not normal (e.g., it is acquired very slowly and laboriously). It is therefore possible that these patients may possess sufficient remaining episodic memory to allow for the acquisition of semantic knowledge (Squire & Zola, 1998). Another (compatible) possibility is that the acquisition of semantic memory normally makes use of the episodic system, but that other (less efficient) points of entry can be more heavily relied upon when the episodic system is damaged (or has not yet developed fully).

  What might be some of these points of entry? As one might imagine given the prominence of sensorimotor-based models, sensory and motor information that may be acquired implicitly is an obvious candidate. And in fact, there is clear evidence from studies on the development of conceptual knowledge in young children that sensory and motor information are important for developing semantic knowledge about object concepts. Some of this evidence comes from studies examining how young children categorize and make inferences about novel objects. In one study, for example, when 2-year-old children were presented with a novel object and instructed to move it horizontally, they were more likely to consider it to be similar to (i.e., to categorize it with) another novel object whose long axis extended horizontally than to one whose long axis extended vertically, whereas the preference was reversed for children who moved the original novel object vertically (L. B. Smith, 2005). Thus, motor information had an implicit influence on their categorization, which presumably affects their conceptual representations.

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