The cognitive architecture for chaining of two mental operations

Abstract

a b s t r a c tA simple view, which dates back to Turing, proposes that complex cognitive operations are composed of serially arranged elementary operations, each passing intermediate results to the next. However, whether and how such serial processing is achieved with a brain composed of massively parallel processors, remains an open question. Here, we study the cognitive architecture for chained operations with an elementary arithmetic algorithm: we required participants to add (or subtract) two to a digit, and then compare the result with five. In four experiments, we probed the internal implementation of this task with chronometric analysis, the cued-response method, the priming method, and a subliminal forcedchoice procedure. We found evidence for an approximately sequential processing, with an important qualification: the second operation in the algorithm appears to start before completion of the first operation. Furthermore, initially the second operation takes as input the stimulus number rather than the output of the first operation. Thus, operations that should be processed serially are in fact executed partially in parallel. Furthermore, although each elementary operation can proceed subliminally, their chaining does not occur in the absence of conscious perception. Overall, the results suggest that chaining is slow, effortful, imperfect (resulting partly in parallel rather than serial execution) and dependent on conscious control.

A cognitive framework for explaining serial processing and sequence execution strategies

“…This indicates that, first, both processes could be simultaneously activated, possibly because they involve different neural structures, and, second, that they were both triggered by the availability of the required information in short-term memory (for similar findings, see Sudevan & Taylor, 1987). Sackur and Dehaene (2009) argued that consciousness is required to make sure that the prepared processes are used in the proper order. That two central processes may be simultaneously active is further suggested by findings with the Psychological Refractory Period task showing crosstalk when the two successive tasks use the same type of input information (Hommel, 1998;Pashler, 1994).…”

“…Support for this idea comes from a study by Sackur and Dehaene (2009). These researchers had participants carry out two successive mathematical procedures (add two, then compare with five).…”

“…This fits our assumption of a central processor responsible for several central processing stages, flanked by processors at the perceptual and motor level. To prevent accumulation of inaccuracies across stages, each processing stage is assumed to have a constant output quality so that extra processing demands (e.g., when stimulus quality is poor) lead to longer processing durations (Sackur & Dehaene, 2009;Sanders, 1990).…”

Temporal structure coding with and without awareness

“…This model makes the prediction that consciousness is required for specific cognitive tasks, including those for which activity must be amplified and maintained over a sufficient duration for it to become accessible to multiple other processors. Previous results suggest that subliminal priming typically becomes undetectable after a few hundreds of milliseconds (e.g., Mattler, 2005), and that the chaining of cognitive operations is not possible without awareness (Sackur & Dehaene, 2009). These two examples involve all or none criteria, according to which a function is enabled in the presence -but not the absence -of awareness.…”

Can the meaning of multiple words be integrated unconsciously?

“…Generally, although several high-level cognitive processes can be influenced by subliminal stimuli they are likely not executed in the same way as during their conscious versions [2,15]. Influential models as well as experimental data suggest that consciousness is required for multiple-step rule-based algorithms, for example in doing mental arithmetic or performing grammatical language operations [16][17][18]. In contrast to unconscious stimulus processing, which seems relatively fleeting, conscious information processing might be accompanied by recurrent and long-lasting information sharing between distant brain regions.…”