DOCUMENTS

Mertens, G., & De Houwer, J. (2016). The impact of a context switch and context instructions on the return of verbally conditioned fear. Journal of Behavior Therapy and Experimental Psychiatry, 51, 10-18.

Background and Objectives: Repeated exposure to a conditioned stimulus can lead to a reduction of conditioned fear responses towards this stimulus (i.e., extinction). However, this reduction is often fragile and sensitive to contextual changes. In the current study, we investigated whether extinction of fear responses established through verbal threat instructions is also sensitive to contextual changes. We additionally examined whether verbal instructions can strengthen the effects of a context change.
Methods: Fifty-two participants were informed that one colored rectangle would be predictive of an electrocutaneous stimulus, while another colored rectangle was instructed to be safe. Half of these participants were additionally informed that this contingency would only hold when the background of the computer screen had a particular color but not when it had another color. After these instructions, the participants went through an unannounced extinction phase that was followed by a context switch.
Results: Results indicate that extinguished verbally conditioned fear responses can return after a context switch, although only as indexed by self-reported expectancy ratings. This effect was stronger when participants were told that CS-US contingency would depend on the background color, in which case a return of fear was also observed on physiological measures of fear.
Limitations: Extinction was not very pronounced in this study, possibly limiting the extent to which return of fear could be observed on physiological measures.
Conclusions: Contextual cues can impact the return of fear established via verbal instructions. Verbal instructions can further strengthen the contextual control of fear.

Mertens, G., & De Houwer, J. (2016). Potentiation of the startle reflex is in line with contingency reversal instructions rather than the conditioning history. Biological Psychology, 113, 91-99.

In the context of fear conditioning, different psychophysiological measures have been related to different learning processes. Specifically, skin conductance responses (SCRs) have been related to cognitive expectancy learning, while fear potentiated startle (FPS) has been proposed to reflect affective learning that operates according to simple associative learning principles. On the basis of this two level account of fear conditioning we predicted that FPS should be less affected by verbal instructions and more affected by direct experience than SCRs. We tested this hypothesis by informing participants that contingencies would be reversed after a differential conditioning phase. Our results indicate that contingency reversal instructions led to an immediate and complete reversal of FPS regardless of the previous conditioning history. This change was accompanied by similar changes on US expectancy ratings and SCRs. These results conform with an expectancy model of fear conditioning but argue against a two level account of fear conditioning.

Muhle-Karbe, P.S., Duncan, J., De Baene, W., Mitchell, D.J., & Brass, M. (2016). Neural Coding for Instruction-Based Task Sets in Human Frontoparietal and Visual Cortex. Cerebral Cortex.


Task preparation has traditionally been thought to rely upon persistent representations of instructions that permit their execution after delays. Accumulating evidence suggests, however, that accurate retention of task knowledge can be insufficient for successful performance. Here, we hypothesized that instructed facts would be organized into a task set; a temporary coding scheme that proactively tunes sensorimotor pathways according to instructions to enable highly efficient “reflex-like” performance. We devised a paradigm requiring either implementation or memorization of novel stimulus–response mapping instructions, and used multivoxel pattern analysis of neuroimaging data to compare neural coding of instructions during the pretarget phase. Although participants could retain instructions under both demands, we observed striking differences in their representation. To-be-memorized instructions could only be decoded from mid-occipital and posterior parietal cortices, consistent with previous work on visual short-term memory storage. In contrast, to-be-implemented instructions could also be decoded from frontoparietal “multiple-demand” regions, and dedicated visual areas, implicated in processing instructed stimuli. Neural specificity in the latter moreover correlated with performance speed only when instructions were prepared, likely reflecting the preconfiguration of instructed decision circuits. Together, these data illuminate how the brain proactively optimizes performance, and help dissociate neural mechanisms supporting task control and short-term memory storage.

Standard dual process models in the action domain postulate that stimulus-driven
processes are responsible for suboptimal behavior because they take them to be rigid and
automatic and therefore the default. We propose an alternative dual process model in which
goal-directed processes are the default instead. We then transfer the dual process logic from
the action domain to the emotion domain. This reveals that emotional action tendencies are
often attributed to stimulus-driven processes. Our alternative model submits that emotional
action tendencies can also be caused by goal-directed processes. We evaluate the type of
empirical evidence required for validating our model and we consider implications of our
model for behavior change, encouraging strategies focused on the expectancies and values of
action outcomes.

Previous research showed that the repeated approaching of one stimulus and avoiding of another
stimulus typically leads to more positive evaluations of the former stimuli. In the current study,
we examined whether approach and avoidance training (AAT) effects on evaluations of neutral
stimuli can be modulated by introducing a regularity between the approach-avoidance actions
and a positive or negative (feared) stimulus. In an AAT task, participants repeatedly approached
one neutral non-word and avoided another neutral non-word. Half of the participants also
approached a negative fear-conditioned stimulus (CS+) and avoided a conditioned safe stimulus
(CS-). The other half of the participants avoided the CS+ and approached the CS-. Whereas
participants in the avoid CS+ condition exhibited a typical AAT effect, participants in the
approach CS+ condition exhibited a reversed AAT effect (i.e., they evaluated the approached
neutral non-word as more negative than the avoided non-word). These findings provide evidence
for the malleability of the AAT effect when strongly valenced stimuli are approached or avoided.
We discuss the practical and theoretical implications of our findings.

Whereas it is widely recognized that both verbal threat information and stimulus pairings
can install strong and persistent fear, few studies have addressed the interaction between these
two pathways of fear. According to the expectancy bias of Davey (1992, 1997), verbal
information can install expectancy biases for aversive events that can result in facilitated fear
learning through stimulus pairings and can delay extinction of fear. However, these predictions
of the expectancy bias account have not been explored fully. Following up on two earlier studies
(Field & Storksen-Coulson, 2007; Ugland, Dyson, & Field, 2013), we investigated the impact of
prior threat information on fear acquisition, extinction and reinstatement. To this aim,
participants received instructions about four unfamiliar animals, two of which that were
described as dangerous whereas the other two were described as harmless. One animal of each
pair was subsequently paired with an electric stimulus. Our results indicated that threat
information resulted in stronger fear responses prior to fear conditioning and in delayed
extinction of fear. However, these effects of instructions were not very pronounced and not
found on all measures of fear. We discuss several methodological and procedural considerations
that may modulate the effects of (verbally installed) expectancy biases.

In an associative patterning task, some people seem to focus more on learning an
overarching rule, whereas others seem to focus on acquiring specific relations between the
stimuli and outcomes involved. Building on earlier work, we further investigated which
cognitive factors are involved in feature- versus rule-based learning and generalization. To this
end, we measured participants’ tendency to generalize according to the rule of opposites after
training on negative and positive patterning problems (i.e., A+/B+/AB- and C-/D-/CD+), their
tendency to attend to global aspects or local details of stimuli, their systemizing disposition and
their score on the Raven intelligence test. Our results suggest that while intelligence might have
some influence on patterning learning and generalization, visual processing style and
systemizing disposition do not. We discuss our findings in the light of previous observations
on patterning.

The blocking effect has inspired numerous associative learning theories and is widely cited in
the literature. We recently reported a series of 15 experiments that failed to obtain a blocking effect
in rodents. Based on those consistent failures, we claimed that there is a lack of insight into the
boundary conditions for blocking. In his commentary, Soto (in press) argues that contemporary
associative learning theory does provide a specific boundary condition for the occurrence of blocking,
namely the use of same- versus different-modality stimuli. Given that in ten of our 15 experiments
same-modality stimuli were used, he claims that our failure to observe a blocking effect is
unsurprising. We cannot but disagree with that claim, because of theoretical, empirical, and
statistical problems with his analysis. We also address two other possible reasons for a lack of
blocking that are referred to in Soto’s (in press) analysis, related to generalization and salience, and
dissect the potential importance of both. While Soto’s (in press) analyses raises a number of
interesting points, we see more merit in an empirically guided analysis and call for empirical testing
of boundary conditions on blocking.

With the discovery of the blocking effect, learning theory took a huge leap forward, because
blocking provided a crucial clue that surprise is what drives learning. This in turn stimulated the
development of novel association-formation theories of learning. Eventually, the ability to explain
blocking became nothing short of a touchstone for the validity of any theory of learning, including
propositional and other non-associative theories. The abundance of publications reporting a
blocking effect and the importance attributed to it suggest that it is a robust phenomenon. Yet, in
the current paper we report fifteen failures to observe a blocking effect despite the use of
procedures that are highly similar or identical to those used in published studies. Those failures raise
doubts regarding the canonical nature of the blocking effect and call for a reevaluation of the central
status of blocking in theories of learning. They may also illustrate how publication bias influences
our perspective towards the robustness and reliablilty of seemingly established effects in the
psychological literature.

Bundt, C., Bardi, L., Abrahamse, E. L., Brass, M., & Notebaert, W. (2015). It wasn’t me! Motor activation from irrelevant spatial information in the absence of a response. Frontiers in Human Neuroscience, 9, (539).

Embodied cognition postulates that perceptual and motor processes serve higher-order cognitive faculties like language. A major challenge for embodied cognition concerns the grounding of abstract concepts. Here we zoom in on abstract spatial concepts and ask the question to what extent the sensorimotor system is involved in processing these. Most of the empirical support in favor of an embodied perspective on (abstract) spatial information has derived from so-called compatibility effects in which a task-irrelevant feature either facilitates (for compatible trials) or hinders (in incompatible trials) responding to the task-relevant feature. This type of effect has been interpreted in terms of (task-irrelevant) feature-induced response activation. The problem with such approach is that incompatible features generate an array of task-relevant and -irrelevant activations [e.g., in primary motor cortex (M1)], and lateral hemispheric interactions render it difficult to assign credit to the task-irrelevant feature per se in driving these activations. Here, we aim to obtain a cleaner indication of response activation on the basis of abstract spatial information. We employed transcranial magnetic stimulation (TMS) to probe response activation of effectors in response to semantic, task-irrelevant stimuli (i.e., the words left and right) that did not require an overt response. Results revealed larger motor evoked potentials (MEPs) for the right (left) index finger when the word right (left) was presented. Our findings provide support for the grounding of abstract spatial concepts in the sensorimotor system.

Van Dessel, P., De Houwer, J., Gast, A., & Smith, C.T. (2015). Instruction-based approach-avoidance effects: Changing stimulus evaluation via the mere instruction to approach or avoid stimuli. Experimental Psychology, 62, 161-169.

Prior research suggests that repeatedly approaching or avoiding a certain stimulus changes the
liking of this stimulus. We investigated whether these effects of approach and avoidance training occur also when participants do not perform these actions but are merely instructed about the stimulus–action contingencies. Stimulus evaluations were registered using both implicit (Implicit Association Test and evaluative priming) and explicit measures (valence ratings). Instruction- based approach-avoidance effects were observed for relatively neutral fictitious social groups (i.e., Niffites and Luupites), but not for clearly valenced well-known social groups (i.e., Blacks and Whites). We conclude that instructions to approach or avoid stimuli can provide sufficient bases for establishing both implicit and explicit evaluations of novel stimuli and discuss several possible reasons for why similar instruction-based approach-avoidance effects were not found for valenced well-known stimuli.

Van Dessel, P., De Houwer, J., Gast, A., Smith, C. T., & De Schryver, M. (2016). Instructing implicit processes: When instructions to approach or avoid influence implicit but not explicit evaluation. Journal of Experimental Social Psychology, 63, 1-9.

Previous research has shown that linking approach or avoidance actions to novel stimuli through
mere instructions causes changes in the implicit evaluation of these stimuli even when the actions
are never performed. In two high-powered experiments (total N = 1147), we examined whether
effects of approach-avoidance instructions on implicit evaluations are mediated by changes in
explicit evaluations. Participants first received information about the evaluative properties of two
fictitious social groups (e.g., Niffites are good; Luupites are bad) and then received instructions to
approach one group and avoid the other group. We observed an effect of approach-avoidance
instructions on implicit but not explicit evaluations of the groups, even when these instructions
were incompatible with the previously obtained evaluative information. These results indicate
that approach-avoidance instructions allow for unintentional changes in implicit evaluations. We
discuss implications for current theories of implicit evaluation.

Teuchies, M., Demanet, J., Sidarus, N., Haggard, P., Stevens, M. A., & Brass, M. (2016). Influences of Unconscious Priming on Voluntary actions: role of the Rostral Cingulate Zone. Neuroimage, 135, 243–252.


The ability to make voluntary, free choices is fundamental to what it means to be human. A key brain region that is involved in free choices is the rostral cingulate zone (RCZ), which is part of the medial frontal cortex. Previous research has shown that activity in this brain region can be modulated by bottom-up information while making free choices. The current study extends those findings, and shows, for the first time, that activation in the RCZ can also be modulated by subliminal information. We used a subliminal response priming paradigm to bias free and cued choices. We observed more activation in the RCZ when participants made a choice that went against the prime’s suggestion, compared to when they chose according to the prime. This shows that the RCZ plays an important role in overcoming externally-triggered conflict between different response options, even when the stimuli triggering this conflict are not consciously perceived. Our results suggest that an important mechanism of endogenous action in the RCZ may therefore involve exerting an internally-generated action choice against conflicting influences, such as external sensory evidence. We further found that subliminal information also modulated activity in the anterior insula and the supramarginal gyrus.