L7 Long-term memory systems

• Phonological loop and visuospatial sketchpad:

  • They support behaviour on tasks other than memory tasks - ‘working memory’
  • Verbal reasoning e.g. what is 25 + 12
  • Spacial reasoning e.g. mental rotation
• Evidence for STM having a semantic component

  • patients have been identified who cannot repeat more than 1-2 words in a STM task but can speak normally in conversations
  • When asked to repeat sentences word for word they paraphrase
  • Suggests poor phonological STM, but good semantic STM that can store the gist of a sentence
• What does the phonological support?

  Our ability to identify spoken words. No meaning is associated with phonological LTM - this is in semantic LTM
• What does visual LTM support?

  Our ability to identify visual information e.g. words, objects, faces
• What does semantic LTM support?

  Our knowledge of the meaning and function of words and objects. It also supports inferences e.g. an ostrich breathes.
• What does episodic memory do?


  Links memories from various LTM systems to store a record of a personal event.

  
• Single dissociation example for different LTM systems

  Dyslexics have difficulty identifying words but are fine in recognising faces.

  Suggests that LTM for words are faces are stored in different systems.
• Double dissociation example for different LTM systems

  Prosopagnosic patients have more difficulty in identifying faces compared to words.

  Gives much stronger evidence that there are two types of visual LTM - words and faces.
• What are single and double dissociations?

  Single = an experimental manipulation or neurological impairment affects performance on task 1 more than task 2.

  Double = In addition, another experimental manipulation or neurological impairment affects performance in task 2, but not task 1.
• Double dissociation examples - LTM system for sound stimuli can be broken down

  Pure word deafness: patients cannot understand words but can understand environmental sounds e.g. understands meow but not cat.

  Auditory agnosia: can understand spoken words, but not environmental sounds.
• Dissociation example between episodic LTM and phonological STM

  Anterograde amnesic patients e.g. HM have poor episodic memory and good phonological STM.

  Phonological STM patients have poor phonological STM but good episodic memory.
• Dissociation examples between episodic LTM and procedural memory:

  Amnesia selectively impairs episodic memory and procedural memory is fine. e.g. patients learn to draw while looking in a mirror but cannot remember doing it.

  Parkinson’s and Huntington’s disease selectively impairs procedural learning.