Summary of several chapters from Eysenck and Keane’s Cognitive Psychology, sixth edition (2010)
Contrary to early interpretations of shadowing task results, it now appears that unattended stimuli receive considerable processing before being blocked by attentional filters. Theorists continue to debate the relative position of the attentional bottleneck, either early in the auditory processing circuit or late, but the most recent and persuasive evidence favors a flexible early-selection model. Visual attention models are somewhat different: there appears to be at least two interacting attentional systems directed by 1) goals and 2) stimulus. The goal-directed system can be thought of as a divisible spotlight, capable of holding multiple objects in attentional focus at a time.
Of great practical relevance, dual-task performance (where performance of a primary task is impaired by a second task), which can be influenced by task difficulty and similarity as well as by practice, is a productive window on divided attention.
Two broad explanations of dual-task effects have been proposed: First, a central-capacity theory suggests a single, limited, attentional capacity may be stressed by multiple tasks, with support from neuroimaging studies showing underadditivity (i.e., the neural activity correlated with the separate, independent performance of two tasks sum to greater than the activity measure during simultaneous performance of both tasks).
Second, a multiple-resource theory suggests that similar tasks compete for modular resources. Others have suggested a combined theory with features from both central-capacity and multiple-resource theories to best explain the separate lines of evidence supporting both. In this view, a top-down executive subordinates several specialized, semi-autonomous mechanisms. The existence of novel activity in the dorsolateral prefrontal cortex during certain dual-task conditions supports the executive proposition.
As for memory, the multi-store model posits three separate storage / retrieval systems it calls sensory, short-term, and long-term stores. But an improvement on this model, called the working memory system, further explodes the general short-term store concept.
Working memory is thought to be composed of four parts, 1) a central executive distributed over several anatomic brain areas responsible for active inhibition, shifting, updating, dual-task management, and coordinating the general activities of the other parts; 2) a two-component phonological loop with both storage and processing capacities; 3) a similarly composed visuo-spacial sketchpad, and 4) an episodic buffer capable of integration and temporary storage.
That smell sometimes elicits strong, emotion-laden memories is not an insight – the majority of people find such memories to be among their most potent – but an explanation for why this is so would be a considerable achievement. Eysenck and Keane propose several components of the full but unknown answer: First, they suggest that strong memory traces associated with olfaction may be caused by the orbitofrontal cortex’s role in processing elements of both smell and emotion. Second, they observe that, since a great deal of memory is modally related to vision, the rarer odor-modal associations may be more distinctive and isolated, and so better protected from interference. Similarly, third, Eysenck and Keane propose that because language is less associated with olfaction than audition and vision, olfaction-triggered memories may be less targeted by language-associated interference than those triggered by other sensory modalities.
But these explanations seem insufficient to explain the genuinely distinct kind of reminiscence many people experience upon detecting certain odor cues. Dave Porter, professor of psychology at Berea College, recently offered another interesting component. Olfaction is of major significance to most mammals, as is emotion and memory. Though none are exclusive to the clade, their combination and elaboration is distinctly mammalian. Their close evolutionary development and mutually reinforcing contributions to survival (via the four F’s) make it likely that their constituent circuitries remain intricately interconnected, with results such as the olfaction-emotion-memory trifecta here under consideration.
In any case, according to levels-of-processing theory, the way information is processed during learning influences how well we are able to subsequently retrieve it. The theory maintains that perception, attention, and memory are interconnected; that both learning and remembering are byproducts of perception, attention, and comprehension; and that elaboration, distinctiveness, and depth are important processing levels, with depth of processing having the greatest effect on memory. But transfer-appropriate processing theory, which argues feature relevance to a specified learning target is a more salient processing level than depth, is also experimentally supported.
Eysenck, M. W., & Keane, M. T. (2010). Cognitive Psychology: A Student’s Handbook, 6th Edition (6th ed.). Psychology Press.
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