CHAPTER 15
Sensory and Working Memory
JAMES S. NAIRNE
423PROLONGING THE PRESENT: SENSORY MEMORY 424
Measuring Sensory Persistence 424
The Characteristics of Sensory Persistence 425
Modality and Suffix Effects 426
SHORT-TERM OR WORKING MEMORY 427
Forgetting Over the Short Term 427
Capacity Limitations 430
Retrieval of Short-Term Memories 432
The Working Memory Model 434
Simulation Models of Short-Term Memory 437
CONCLUSIONS 439
REFERENCES 440To remember is to conjure up an image of the distant past, or
perhaps a reflection from hours or days previous. Yet we re-
member over the very short term as well—over time periods
lasting minutes, seconds, and even milliseconds. Consider
language: We need to remember the early parts of a spoken
phrase, or the particular sequence of phonemes in a word, for
periods lasting beyond their physical presentation. Such
short-lived memories are widely believed to be adaptive
components of on-line cognitive processing. They help us
produce and interpret spoken language, remember telephone
numbers, reason, solve problems, and even think. The pur-
pose of this chapter is to review and comment on the psy-
chology of these transient memories.
Traditionally, memory researchers have distinguished
between two types of transient memories: sensory memo-
ries and short-term memories. Sensory memoriesare faith-
ful, veridical records of initiating stimuli. You can think of
a sensory memory as a kind of continuation of the actual
event—the same information simply removed in time
(Crowder & Surprenant, 2000). By definition, then, sensory
memories are modality specific: Visual stimuli lead to vi-
sual sensory memories, auditory stimuli lead to auditory
sensory memories, tactile stimuli produce tactile sensory
memories, and so on. Sensory memories tend to last for
only a second or two, at best, and are widely thought to ac-
crue from the processes involved in normal sensation and
perception.
Short-term memoriesare the active, but analyzed, contents
of mind. Any time that we form a conscious idea, or process
incoming information from the world, we activate existing
long-term memory structures; as a collective set, this acti-
vated knowledge defines what most psychologists currently
mean by short-term memory (e.g., Cowan, 1995; Shiffrin,
1999). Short-term memories, unlike sensory memories, need
not accurately reflect a just-presented stimulus. Instead, they
usually represent meaningful interpretations of what has just
occurred. For example, we might see a string of visual forms
representing the letters P U M P K I N, but actively maintain
a short-term memory for the wordpumpkinand perhaps even
a visual image of the orange object itself. Evidence suggests
that short-term memories are often represented in the form of
an acoustic code—an inner voice—which probably plays a
vital role in the interpretation and production of spoken lan-
guage (e.g., Baddeley, Gathercole, & Papagno, 1998).
Psychologists use an additional term, working memory,to
refer to the set of processes, or systems, that control and
maintain activation of short-term memories (Baddeley, 1986;
Miyake & Shah, 1999). Activation is assumed to be inher-
ently fragile, so short-term memories are quickly lost in the
absence of some kind of maintenance process. The working
memory system is thought to contribute to virtually all as-
pects of cognitive processing (e.g., reading, reasoning, prob-
lem solving, etc.), but this chapter focuses solely on the task
of remembering over the short term. What are the character-
istics of memory over the short term? How does memory
over the short term differ from long-term memory? Are
different systems or mnemonic principles needed to explain
short- and long-term remembering? To begin, I turn to the