BHS 499-07 Models of Memory

Memory and Amnesia Plato’s Model z Plato extended the wax tablet metaphor to refer to birds in an aviary. • Birds are located in specific places. • Search processes are needed to hunt for them. z William James referred to primary and secondary memory. • New experiences linger briefly and need not be stored forever (secondary memory). The Modal (Multi-Store) Model of Memory z Modal refers to sensory modality (way of receiving info from outside world). z Heuristic means “rule of thumb” – this theory of stages is a way of thinking about memory not to be taken literally. z This multistore (modal) model was the guiding framework for decades. Multiple Memory Systems z Memory is not unitary but consists of several subcomponents (parts). z Atkinson & Shifrin: • Sensory store, short term, long term stores z Tulving’s Triarchic Theory: • Episodic Autonoetic (self) • Semantic Noetic (formal knowledge) • Procedural Anoetic (automatic skills) Other Classifications z Declarative vs Nondeclarative • Declarative includes episodic and semantic memory • Nondeclarative includes procedural memory, classical conditioning and priming z Explicit vs implicit • Explicit memory involves consciousness, implicit does not. Beyond Multi-store Models z Levels of processing theory (Craik & Tulving) – it isn’t where memories are processed that matters, but how. • Shallow vs deep processing • Elaborative rehearsal vs repetitive rehearsal z Short term memory was replaced by Baddeley’s model of the central executive (where rehearsal takes place). Current Issues z Neurological bases for memory z Impact and importance of emotion on memory z Use of multiple memory sources (fuzzy trace theories) z Embodied cognition – how our grounding in the world influences memory Sensory Memory z Three sensory registers discussed by Randvansky and Parkin texts: • Visual sensory register (iconic memory) • Auditory sensory register (echoic memory) • Touch sensory register (haptic memory) z Briefest duration -- < 5 sec z Retains characteristics of the stimulus so that meaning can be interpreted Sperling’s partial report procedure showed greater recall when a tone cued people to look at a specific line immediately after viewing the stimulus, but not after a delay. Iconic Memory z How many items, how long does it last? z It is difficult to study the capacity of iconic memory because items fade before people can report them aloud. • Averbach found that increased presentation time did not improve memory for dots. • Sperling’s partial report procedure showed that an entire array was remembered well, but only for ~.250 seconds, ¼ sec. Anorthoscopic Perception z Images in the iconic register are combined to form a single mental representation. z Anorthoscopic perception (seeing more than is there) – an image is passed through a slit at 250-300 ms (quickly). • The original icon is compressed to build up the entire representation – so not an after image but a constructive process. Trans-Saccadic Memory z Saccade – an eye movement (~ 30 ms). • Our eyes are constantly moving over the objects in the world. z Fixation – when eyes stop on a point (typically ~ 300 ms). z A trans-saccadic memory is needed to build-up a mental representation from all of the eye movements Change Blindness z Visual memory is not always accurate. • Movies frequently contain errors of detail that go unnoticed – continuity errors • Only 33% of subjects noticed the change of an actor of the same ethnicity & gender. z Top-down expectations affect what is noticed. • Students notice students not construction workers, or changes that belong in a scene. Echoic Memory z Echoic memory lasts briefly to permit a mental representation to be formed. • More exists in memory than can be reported. • Retention of info is longer (~ 4 sec). z Because sounds can only be heard once, info is kept available longer. z Flow of speech is constructed from a series of passing sounds. Haptic Memory z Less studied. z Air jets were used in a whole/partial report procedure. • Duration was ~ 1.3 seconds. Short Term Memory z Dispute – is short term memory qualitatively different from long-term memory? • Or is it just the part of long term memory that is currently active? z Severely limited in capacity (unlike sensory registers). • Miller’s magic number of 7 +/- 2 (or 4 +/- 1). Chunking z We are capable of thinking about more by forming units out of smaller pieces of information. • The number of chunks is the same as the number of units that can be remembered. z Prior knowledge guides the chunking process. • Race lengths, chess games are large chunks S.F.’s digit span improved with practice as he learned to chunk digits in terms of race results. Duration of STM z Without active attention, info is forgotten in ~ 30 sec (some sources say 15) • How do you tell people not to think about something so you can test it? z Is forgetting due to decay or interference? • Decay -- passage of time erases trace. • Interference – new info displaces the old STM Retrieval z Does retrieval involve a serial or a parallel search? • Sternberg’s paradigm of digits followed by a probe showed serial exhaustive search. • Most people find this result surprising, showing why self-report may be flawed. • An alternative explanation is parallel search with limited resources (requiring more time). z Most likely both processes are involved. Serial Position Curves z Position in a list of items affects likelihood of being recalled. z Primacy effect – items at the beginning of a list are remembered better. • Due to encoding in long term memory via more rehearsal. z Recency effect – items at the end of the list are remembered well because still active in short term memory. Modifying Serial Position Effects z Placing an irrelevant item at the end of a list eliminates the recency effect. z Memory for actions is different – no primacy effect because the focus is on individual actions so less rehearsal. z Suffix effect – recency effect is diminished when new info is added at the end (the more the greater the effect). Memory for Order of Items z The position of the item must be remembered, not the item itself. z Slot-based models – info is dropped into a series of slots, read off in order. z Chaining models – associative links form a chain (but items can be skipped). z Perturbation model – hierarchy of chunks is disturbed. More Serial Order Models z Inhibition models – retrieval starts with the most active, then inhibits it and goes to the second most active, and so on… • Inhibition prevents things just recalled from being recalled again immediately. • Repetition blindness – people fail to see the same word presented soon after it was first seen on a screen. z Context-based models – order tied to context.