Academic journal article Attention, Perception and Psychophysics

Unconscious Priming of Task Sets:: The Role of Spatial Attention

Academic journal article Attention, Perception and Psychophysics

Unconscious Priming of Task Sets:: The Role of Spatial Attention

Article excerpt

Published online: 5 October 2011

© Psychonomic Society, Inc. 2011

Abstract Unconscious stimuli activate task sets, mental programs that orchestrate performance of complex tasks, but the role of attention in such effects has not been addressed. In previous studies, unconscious prime stimuli appeared at attended locations and were explicitly specified in the task instructions; spatial attention to the prime and/or a specific conscious attentional set may thus be required for such unconscious activation to arise. In the present experiments, a learning phase established associations between unconscious prime stimuli and performance of two tasks. These associations influenced task performance in a subsequent test phase, even though the primes were not specified in current task instructions. This is the first demonstration that unconscious stimuli can prime task sets independently of a current attentional set that specifies stimulus-task mappings. Such priming was not influenced by spatial attention cues, in contrast to clear attention influences in comparison trials that mimicked conditions employed by previous studies.

Keywords Unconscious perception . Priming . Cognitive control . Attention . Executive . Dorsolateral prefrontal cortex . dlPFC


Perceptual, semantic, and motor functions can all be influenced by stimuli that fail to meet objectively defined thresholds for conscious perception (Cheesman & Merikle, 1986; Dehaene et al., 1998; Enns & Di Lollo, 2004; Klapp, 2007; Klotz & Neumann, 1999; Kouider & Dehaene, 2007; Mattler, 2003, 2005; Sumner, Tsai, Yu, & Nachev, 2006), including very high level processes (Dijksterhuis, Bos, Nordgren, & van Baaren, 2006; Ferguson & Bargh, 2004). In contrast, executive processes of cognitive control, which operate to prevent reflexive processing from dominating cognition and action and to guide rule-based responses to stimuli, have been widely assumed to require conscious attention (Baars, 1989; Dehaene & Naccache, 2001; Jack & Shallice, 2001; Norman & Shallice, 1986). This apparent exclusive preserve of conscious processing has shaped influential theories about likely functions of consciousness in both cognitive science and philosophy. However, three recent studies have claimed that executive functions can be triggered unconsciously, in apparent contradiction of these views.

Lau and Passingham (2007) examined the effects of unconsciously perceived stimuli on participants' preparation to perform one of two word tasks (semantic or phonological). Under such conditions, executive processes select the requisite mental programs, or task sets, to perform one task and inhibit responses associated with another (DiGirolamo et al., 2001; Wylie, Javitt, & Foxe, 2006). On each trial of their study, a conscious task instruction (a diamond or square) signaled which of the two tasks the participant should perform. The instruction appeared only 150 ms prior to the target word, ensuring that necessary mental preparations to perform the task (i.e., to establish a particular dominant task set) would be incomplete when the word appeared. An unconscious prime stimulus (again a diamond or square) was also presented shortly prior to the instruction: On half the trials, this unconscious stimulus was congruent with the instruction in that it signaled the same task, and on the other half, it was incongruent with the instruction, signaling the other task. Responses to the word tasks were significantly faster when prime and instruction were congruent (i.e., signaled the same task) than when they were incongruent (signaled different tasks), suggesting that the unconscious prime had influenced task set selection.

One factor that arguably complicated the interpretation of Lau and Passingham's (2007) findings is that they employed unconscious primes that were the same shapes as the conscious task instructions. Thus, whenever the prime and instruction signaled the same task, they were the same shape, but they were different shapes when they signaled different tasks. …

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