Research Article: Attentional sensitization of unconscious visual processing: Top-down influences on masked priming

Date Published: February 15, 2012

Publisher: University of Finance and Management in Warsaw

Author(s): Markus Kiefer, Sarah C. Adams, Monika Zovko.


Classical theories of automaticity assume that automatic processes elicited by
unconscious stimuli are autonomous and independent of higher-level cognitive
influences. In contrast to these classical conceptions, we argue that automatic
processing depends on attentional amplification of task-congruent processing
pathways and propose an attentional sensitization model of unconscious visual
processing: According to this model, unconscious visual processing is automatic
in the sense that it is initiated without deliberate intention. However,
unconscious visual processing is susceptible to attentional top-down control and
is only elicited if the cognitive system is configured accordingly. In this
article, we describe our attentional sensitization model and review recent
evidence demonstrating attentional influences on subliminal priming, a
prototypical example of an automatic process. We show that subliminal priming
(a) depends on attentional resources, (b) is susceptible to stimulus
expectations, (c) is influenced by action intentions, and (d) is modulated by
task sets. These data suggest that attention enhances or attenuates unconscious
visual processes in congruency with attentional task representations similar to
conscious perception. We argue that seemingly paradoxical, hitherto unexplained
findings regarding the automaticity of the underlying processes in many
cognitive domains can be easily accommodated by our attentional sensitization
model. We conclude this review with a discussion of future research questions
regar-ding the nature of attentional control of unconscious visual

Partial Text

Unconscious automatic processes are traditionally thought to occur autonomously and
independently of top-down control (Posner &
Snyder, 1975; Schneider & Shiffrin,
1977). According to classical theories, automatic processes (a) are
independent of capacity-limited attentional resources, (b) are not prone to
interference from other processes, (c) can act in parallel, and (d) are unconscious
(Posner & Snyder, 1975; Schneider & Shiffrin, 1977). Top-down
control by attention, action goals, and task sets is assumed to be restricted to
processes that are conscious.

Although refined theories of automaticity converge on the assumption that automatic
processes are susceptible to top-down control, there is as yet no general
theoretical framework that accounts for a number of top-down factors and different
forms of automatic processes. We have therefore recently developed the attentional
sensitization model of unconscious cognition (Kiefer
& Martens, 2010) that aims at explaining the various influences of
top-down attention on different forms of unconscious automatic processing. According
to this model, attentional influences originating from task sets enhance
task-relevant unconscious processes while attenuating task-irrelevant unconscious
processes. Much as conscious perception is influenced by attentional mechanisms,
unconscious cognition is assumed to be controlled by top-down signals from
prefrontal cortex (Haynes et al., 2007) that
increase or decrease the sensitivity of processing pathways for incoming sensory
input (Bode & Haynes, 2008; Hopfinger, Buonocore, & Mangun, 2000; Hopfinger, Woldorff, Fletcher, & Mangun,
2001). Processing in task-relevant pathways is enhanced by increasing the
gain of the neurons in the corresponding areas, whereas processing in
task-irrelevant pathways is attenuated by a decrease of the gain (Reynolds, Pasternak, & Desimone, 2000).
Gain is a parameter in neural network modeling, which
influences the probability that a neuron fires at a given activation level (Hamker, 2005). Single cell recordings in
non-human primates have shown that the likelihood of a neuron firing, given a
constant sensory input, is enhanced when the stimulus dimension that is
preferentially processed by the neuron is attended to (e.g., Treue & Martínez-Trujillo, 1999). We thus assume that
an attentional sensitizing mechanism gradually enhances and attenuates stimulus
processing irrespective of whether the stimulus is consciously perceived or not
(Kiefer & Martens, 2010).

Although the classical view of automaticity is prevailing and still dominates current
research, evidence for attentional top-down control of unconscious visual processing
has been accumulated during the last years. Several attentional manipulations have
been shown to reliably modulate subliminal priming effects. This highlights the
generality and robustness of attentional effects on unconscious visual processing.
In this section, we review findings from studies demonstrating that subliminal
priming (a) depends on attentional resources, (b) is susceptible to stimulus
expectations, and (c) is influenced by action intentions.

Unconscious priming does not only depend on action intentions, but also on task sets,
which are active during the presentation of the masked prime (Kiefer, 2007; Kiefer &
Martens, 2010; Martens et al.,
2011). Similar to intentions, task sets are assumed to trigger an
attentional sensitization mechanism that enhances processes in task-congruent
pathways while attenuating task-incongruent processes. In this section, we review
results of recent studies with the induction task paradigm that allows specifying
attentional influences originating from task sets on various forms of unconscious
visual processing at a fine-grained level. The induction task paradigm has been
developed to test specific predictions of the attentional sensitization model, but
can be generally used to identify the influence of task sets on conscious or
unconscious visual perception.

In the previous sections, we have reviewed recent findings demonstrating attentional
influences on unconscious visual processing. Accumulating evidence demonstrates that
unconscious visual processing is susceptible to attentional control similar to
conscious visual processing: Subliminal priming effects, prototypical examples of
automatic processes, are modulated by attentional resources, stimulus expectations,
action intentions, and task sets. Hence, in contrast to classical theories of
automaticity (Posner & Snyder, 1975;
Schneider & Shiffrin, 1977),
automatic processes elicited by unconscious visual stimuli are under attentional
control to some extent. The findings reviewed here are generally in line with
refined theories of automaticity (Moors & De
Houwer, 2006; Naccache et al.,
2002; Neumann, 1990). They
specifically support the notion of attentional sensitization of processing pathways
that enhances and attenuates automatic processing elicited by unconsciously
perceived stimuli in congruency with task representations (Kiefer, 2007; Kiefer &
Martens, 2010). We propose that processing can occur automatically in the
sense that it does not depend on conscious awareness and that it is initiated
without deliberate intention. However, automatic processing is susceptible to
attentional top-down control and is only elicited if the cognitive system is
configured accordingly. Thus, unconscious automatic processing and the notion of
attentional control is not a contradiction as it has been previously thought (Maxfield, 1997; Pessoa et al., 2002; Posner &
Snyder, 1975; Schneider & Shiffrin,

The implicit top-down control of unconscious processing by attentional sensitization
reviewed in this article evidences the adaptability of the cognitive system in
optimizing ongoing processing toward the pursuit of an intended goal: Task-relevant
information is prioritized and task-irrelevant, possibly interfering influences are
attenuated, both at a conscious and an unconscious level. The unconscious processing
streams are thus under the control of higher-level attention to some extent. The
proposed attentional sensitization mechanism operates in such a fashion as to
considerably reduce the risk that unintended and not goal-related unconscious
processes determine cognition and eventually influence behavior (Kiefer & Martens, 2010).




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