Online research in philosophy

Single-unit data from the cortex of monkeys performing working-memory tasks support the main point of the target article. Those data, however, also indicate that the activation of long-term memory is essential to the processing of all cognitive functions. The activation of cortical long-term memory networks is a key neural mechanism in attention (working memory is a form thereof), perception, memory acquisition and retrieval, intelligence, and language.

Different hypotheses about the mechanisms underlying working memory lead to different predictions about working memory capacity when information is distributed across the two hemispheres. We present preliminary data suggesting that memory scanning time (a parameter often associated with working memory capacity) varies depending on how information is subdivided across hemispheres. The data are consistent with a distributed model of working memory.

Memory researchers have discussed the relationship between consciousness and memory frequently in the last few decades. Beginning with research by Warrington and Weiskrantz (1968; 1970), memory has been shown to influence task performance even without awareness of retrieval. Data from amnesic patients show that a study episode influences task performance despite their lack of conscious memory for the study session. More recently, issues of intentionality, awareness, and the relationship between conscious and unconscious forms of memory have come to the forefront. Conscious memory has sometimes been defined by intention to retrieve and sometimes by awareness of retrieval. This distinction has been debated as measurement methodologies have developed. In addition, the functional relationship between conscious and automatic forms of memory has implications for measurement of memory processes and the development of models of memory task performance. Several measurement techniques for conscious and automatic memory are reviewed. The current state of these issues is also discussed.

Recent experimental findings reveal dissociations of conscious and nonconscious performance in many fields of psychological research, suggesting that conscious and nonconscious effects result from qualitatively different processes. A connectionist view of these processes is put forward in which consciousness is the consequence of construction processes taking place in three types of working memory in a specific type of recurrent neural network. The recurrences arise by feeding back output to the input of a central (representational) network. They are assumed to be intemalizations of motor-sensory feedback through the environment. In this manner, a subvocal-phonological, a visuo-spatial, and a somatosensory working memory may have developed. Representations in the central network, which constitutes long-term memory, can be kept active by rehearsal in the feedback loops. The sequentially recurrent architecture allows for recursive symbolic operations and the formation of (auditory, visual, or somatic) models of the external world which can be maintained, transformed and temporarily combined with other information in working memory. Moreover, the quasi-input from the loop directs subsequent attentional processing. The view may contribute to a formal framework to accommodate findings from disparate fields such as working memory, sequential reasoning, and conscious and nonconscious processes in memory and emotion. In theory, but probably not very soon in practice, such connectionist models might simulate aspects of consciousness.

The process-dissociation procedure has been used in a variety of experimental contexts to assess the contributions of conscious and unconscious processes to task performance. To evaluate whether motivation affects estimates of conscious and unconscious processes, participants were given incentives to follow inclusion and exclusion instructions in a perception task and a memory task. Relative to a control condition in which no performance incentives were given, the results for the perception task indicated that incentives increased the participants' ability to exclude previously presented information, which in turn both increased the estimate of conscious processes and decreased the estimate of unconscious processes. However, the results also indicated that incentives did not influence estimates of conscious or unconscious processes in the memory task. The findings suggest that the process-dissociation procedure is relatively immune to influences of motivation when used with a memory task, but that caution should be exercised when the process-dissociation is used with a perception task.

The target article differentiates a new, syntactic component in verbal working memory. We suggest that several more components could be differentiated to make a model of working memory complete. Next, syntax is not always separable from the subject's verbal memory capacity as measured by standard working memory tasks. Finally, interference between different processes cannot be taken as evidence for the processes sharing the same resources. Interference might be a result of active mutual inhibition.

The limited capacity of immediate memory “rides” on the even more limited capacity of consciousness, which reflects the dynamic activity of the thalamocortical core of the brain. Recent views of the conscious narrow-capacity component of the brain are explored with reference to global workspace theory (Baars 1988; 1993; 1998). The radical limits of immediate memory must be explained in terms of biocognitive brain architecture.

Working-memory retention as activated long-term memory fails to capture orchestrated processing and storage, the hallmark of the concept of working memory. The event-related potential (ERP) data are compatible with working memory as a mental workspace that holds and manipulates information on line, which is distinct from long-term memory, and deals with the products of activated traces from stored knowledge.