The functional relationship between recognition memory and conscious awareness was examined in two experiments in which subjects indicated when recognizing a word whether or not they could consciously recollect its prior occurrence in the study list. Both levels of processing and generation effects were found to occur only for recognition accompanied by conscious recollection. Recognition in the absence of conscious recollection, although less likely, was generally reliable and uninfluenced by encoding conditions. These results are consistent with dual-process theories of recognition, which assume that recognition and priming in implicit memory have a common component. And they strengthen the case for making a functional distinction between episodic memory and other memory systems.The function of conscious awareness in memory has gained a fresh importance in contemporary memory research. This importance stems largely from two related sets of findings: neuropsychological findings from studies with amnesic patients and findings of related patterns of functional dissociation from studies with memoryunimpaired adults. Both sets of findings can be described in terms of the distinction that has been made between explicit and implicit memory tests (Graf & Schacter, 1985; see Schacter, 1987, for a recent review). Explicit memory tests are those in which subjects are asked to remember, in the sense of being able consciously to recollect, prior events and experiences. Such tests include conventional episodic memory tests such as recognition and recall. Implicit memory tests are those in which the conscious recollection of prior events and experiences is not required. Such tests include perceptual identification, lexical decision, and word-stem and word-fragment completion. The priming effects observed in these implicit memory tests (superior performance on items that have been previously encountered in the experiment) are the hub of both related sets of findings. Despite their very poor performance in explicit memory tests, amnesic patients have often been found to exhibit normal or nearnormal priming effects, and, in memory-unimpaired adults, priming effects typically have been found either to be uninfluenced by variables, such as levels of processing, that have large effects in explicit memory, or to be influenced in opposite ways by such variables. Unquestionably, therefore, there are fundamental differences in the nature of the memory observed in tests of explicit and implicit memory, and the function of conscious awareness is pivotally important to these differences.

The functional relationship between memory and consciousness was investigated in two experiments in which subjects indicated when recognizing an item whether they could consciously recollect its prior occurrence in the study list or recognized it on some other basis, in the absence of conscious recollection. Low-frequency words, relative to high-frequency words, enhanced recognition accompanied by conscious recollection but did not influence recognition in the absence of conscious recollection. By contrast, nonwords compared with words enhanced recognition in the absence of conscious recollection and reduced recognition accompanied by conscious recollection. A third experiment showed that confidence judgments in recognizing nonword targets corresponded with recognition performance, not with recollective experience. These measures of conscious awareness therefore tap qualitatively different components of memory, not some unitary dimension such as "trace strength." The findings are interpreted as providing further support for the distinction between episodic memory and other memory systems, and also as providing more qualified support for theories that assume that recognition memory entails two components, one of which may also give rise to priming effects in implicit memory.

The functional relation between recognition memory and conscious awareness was assessed in an experiment in which undivided attention at study was compared with two divided attention conditions, one more demanding than the other. When recognizing a word from the study list, subjects indicated whether they could consciously recollect its prior occurrence or recognized it on some other basis, in the absence of conscious recollection. Divided attention at study progressively impaired word recognition accompanied by conscious recollection. Recognition in the absence of conscious recollection was not affected by divided attention. These findings are interpreted as providing further support for the idea that recognition memory entails two distinct components, one based on associative and contextual information, the other based on a "traceless" awareness of familiarity.Recognition can be defined as what happens when an individual identifies a stimulus as having been encountered previously. Conscious awareness of recognition seems to take at least two distinct forms. A stimulus may evoke recognition when its oecurrence brings to mind some specific experience in which the stimulus was previously involved. Alternatively, a stimulus may give rise only to feelings of familiarity. For example, one can recognize a person as being familiar without remembering who the person is, or without being able to recollect anything about the person.A laboratory measure of these two kinds of conscious awareness is provided by Tulving's (1985b) distinction between "remember" and "know" responses. Word recognition measured by a "remember" response indicates that recognizing the word brings back to mind some conscious recollection of its prior oecurrence in the study list, such as an assoeiation or image it triggered, something about its position or appearance, or something of more personal significance. Recognition measured by a "know" response indicates that recognizing the word brings nothing else to mind-no assoeiation, no contextual information, no conscious recollection of its prior occurrence in the study list.Previous studies that have exploited these measures of conscious awareness in recognition memory have shown that they reflect distinct components in performance. Variables such as levels of proeessing, generate versus read, word frequency, and retention interval have influenced only recognition accompanied by recollective experience, as measured by "remember" responses; recognition in the absence of recollective experience, as measured by "know" responses, has been uninfluenced by any ofthese variables (Gardiner, 1988;Gardiner & Java, 1989. Motivated by the striking similarity between variables that dissoeiate "remember' and "know" judgments and those that dissoeiate explicit and implicit memory phenomena more generally, Gardiner and Java (1990; see also Gardiner, 1988) have suggested that the distinction between "remember" and "know" responding can be interpreted within a theoretical framework (Hayman & Tulving, 1989) that com...

The old yellow enzyme (OYE) family is a large group of flavin‐dependent redox biocatalysts with major applications in the industrial reduction of activated alkenes. These enzymes have broad specificity, are relatively stable, and have been made available in large quantities by using conventional genetic methods. The catalytic cycle comprises two half‐reactions: reduction of flavin mononucleotide by NAD(P)H followed by flavin oxidation through stereospecific reduction of the CC bond of a wide range of activated alkenes. Recent years have witnessed extensive investigation of these reactions, aided by knowledge of atomic resolution structures for selected family members. In turn, this has led to deep understanding of the stereochemical course of substrate reduction and expansion of the biocatalytic versatility of this enzyme family through engineering approaches. We provide an overview of the structures, mechanisms, and chemical specificity of the reactions catalyzed by the OYE members. We provide an overview of the biocatalytic potential of this family of enzymes and illustrate the value of combining mechanistic and structural studies of biocatalysts to guide future exploitation of these enzymes in industrial biocatalysis.

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