Tulving published over 300 research articles and chapters, and he is widely cited, with an
h-index of 124 (as of April 2024), and in a
Review of General Psychology survey, published in 2002, he ranked as the 36th most cited psychologist of the 20th century. His published works in 1970s were particularly notable because they coincided with a new determination by many cognitive psychologists to confirm their theories in neuroscience using brain-imaging techniques. During this period, Tulving mapped the areas of the brain, which are considered active during the encoding and retrieval of memory, effectively associating the medial temporal lobe and the hippocampus with episodic memory. a model of brain hemisphere specialization for episodic memory, and discovery of the Tulving-Wiseman function.
Episodic and semantic memory Tulving first made the distinction between
episodic and
semantic memory in a 1972 book chapter. Episodic memory is the ability to consciously recollect previous experiences from memory (e.g., recalling a recent family trip to Disney World), whereas semantic memory is the ability to store more general knowledge in memory (e.g., the fact that Disney World is in Florida). This distinction was based on theoretical grounds and experimental psychology findings, and subsequently was linked to different neural systems in the brain by studies of brain damage and neuroimaging techniques. At the time, this type of theorizing represented a major departure from many contemporary theories of human learning and memory, which did not emphasize different kinds of subjective experience or brain systems. Tulving's 1983 book
Elements of Episodic Memory elaborated on these concepts, and has been cited over 9000 times. According to Tulving, the ability to travel back and forward in time mentally is unique to humans and this is made possible by the
autonoetic consciousness and is the essence of episodic memory.
Encoding specificity principle Tulving's theory of "encoding specificity" emphasizes the importance of retrieval cues in accessing episodic memories. The theory states that effective retrieval cues must overlap with the to-be-retrieved memory trace. Because the contents of the memory trace are primarily established during the initial encoding of the experience, retrieval cues will be maximally effective if they are similar to this encoded information. Tulving has dubbed the process through which a retrieval cue activates a stored memory "synergistic ecphory". One implication of the encoding specificity principle is that forgetting may be caused by the lack of appropriate retrieval cues, as opposed to decay of a memory trace over time or interference from other memories. Another implication is that there is more information stored in memory relative to what can be retrieved at any given point (i.e., availability vs. accessibility).
Amnesia and consciousness Tulving's research has emphasized the importance of episodic memory for our experience of consciousness and our understanding of time. For example, he conducted studies with the amnesic patient
KC, who had relatively normal semantic memory but severely impaired episodic memory due to brain damage from a motorcycle accident. Tulving's work with KC highlighted the central importance of episodic memory for the subjective experience of one's self in time, an ability he dubbed "autonoetic consciousness". KC lacked this ability, failing to remember prior events and also failing to imagine or plan for the future. Tulving also developed a cognitive task to measure different subjective states in memory, called the "remember"/"know" procedure. This task has been used extensively in cognitive psychology and neuroscience.
Implicit memory and priming Tulving made a distinction between conscious or
explicit memory (such as episodic memory) and more automatic forms of
implicit memory (such as
priming). Along with one of his students,
Daniel Schacter, Tulving provided several key experimental findings regarding implicit memory. The distinction between implicit and explicit memory was a topic of debate in the 1980s and 1990s. Tulving and colleagues proposed that these different memory phenomena reflected different brain systems. Others argued that these different memory phenomena reflected different psychological processes, rather than different memory systems. These processes would be instantiated in the brain, but they might reflect different aspects of performance from the same memory system, triggered by different task conditions. More recently, theorists have come to adopt components of each of these perspectives. ==Estonian Studies Foundation==