Maes, E., Krypotos, A. M., Boddez, Y., Alfei, J. M, D’Hooge, R., De Houwer, R., & Beckers, T. (in press). Failures to replicate blocking are surprising and informative – Reply to Soto (in press). Journal of Experimental Psychology: General.
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.
Unpronounceable strings of 4 consonants (conditioned stimuli: CSs) were consistently
followed by familiar words belonging to one of two opposed semantic categories
(unconditioned stimuli: USs). Conditioning, in the form of greater accuracy in rapidly
classifying USs into their categories, was found when visually imperceptible (to most
subjects) CSs occupied ≥ 58 ms of a 75-ms CS–US interval. When clearly visible CSs
were presented in a 375 ms CS–US interval, conditioning was strongly correlated with
measures of contingency awareness, and did not occur in the absence of that awareness.
These experiments delineated two forms of conditioning: Unconscious conditioning
occurred with a brief CS–US interval, with an effectively masked CS, and with no
reportable knowledge of the contingent CS–US relation. Conscious conditioning
occurred with a substantially longer CS–US interval, a perceptible CS, and with subjects’
reportable knowledge of the contingent CS–US relation.
De Houwer, J., Hughes, S., & Brass, M. (2017). Toward a unified framework for research on instructions and other messages: An introduction to the special section on the power of instructions. Neuroscience and Biobehavioral Reviews, 81, 1-3.
Instructions are known to have a profound impact on human behavior. Nevertheless, research
on the effects of instructions is relatively scarce and scattered across different areas of
research in psychology and neuroscience. The current issue of this journal contains six papers
that review research on instructions in different research areas. In this introduction to the
special section, we provide the outline of a framework that focuses on five components that
can be varied in research on this topic (sender, message, receiver, context, and outcome). The
framework brings order to the boundless potential variability in research on the effects of
messages (i.e., it has heuristic value) and highlights that past research explored only a tiny
fraction of what is possible (i.e., it has predictive value). Moreover, it reveals that research in
different areas tends to examine different instantiations of the five components. The latter
observation implies that much can be gained from closer interactions between researchers
from different areas.
Braem, S., De Houwer, J., Demanet, J, Yuen, K. S. L., Kalisch, R., & Brass, M. (2017). Pattern analyses reveal separate experience-based fear memories in the human right amygdala. Journal of Neuroscience, 37, 8116–8130.
Learning fear via the experience of contingencies between a conditioned stimulus (CS) and an
aversive unconditioned stimulus (US) is often assumed to be fundamentally different from
learning fear via instructions. An open question is whether fear-related brain areas respond
differently to experienced CS-US contingencies than to merely instructed CS-US contingencies.
Here, we contrasted two experimental conditions where subjects were instructed to expect the
same CS-US contingencies while only one condition was characterized by prior experience with
the CS-US contingency. Using multi-voxel pattern analysis of fMRI data, we found CS-related
neural activation patterns in the right amygdala (but not in other fear-related regions) that
dissociated between whether a CS-US contingency had been instructed and experienced versus
merely instructed. A second experiment further corroborated this finding by showing a
category-independent neural response to instructed and experienced, but not merely instructed,
CS presentations in the human right amygdala. Together, these findings are in line with
previous studies showing that verbal fear instructions have a strong impact on both brain and
behaviour. However, even in the face of fear instructions, the human right amygdala still shows
a separable neural pattern response to experience-based fear contingencies.
Borragan, G., Slama, H., Destrebecqz, A., & Peigneux, P. (2016). Cognitive Fatigue Facilitates Procedural Sequence Learning. Front Hum Neurosci, 10, 86. doi: 10.3389/fnhum.2016.00086
Enhanced procedural learning has been evidenced in conditions where cognitive control is diminished, including hypnosis, disruption of prefrontal activity and non-optimal time of the day. Another condition depleting the availability of controlled resources is cognitive fatigue (CF). We tested the hypothesis that CF, eventually leading to diminished cognitive control, facilitates procedural sequence learning. In a two-day experiment, 23 young healthy adults were administered a serial reaction time task (SRTT) following the induction of high or low levels of CF, in a counterbalanced order. CF was induced using the Time load Dual-back (TloadDback) paradigm, a dual working memory task that allows tailoring cognitive load levels to the individual's optimal performance capacity. In line with our hypothesis, reaction times (RT) in the SRTT were faster in the high- than in the low-level fatigue condition, and performance improvement was higher for the sequential than the motor components. Altogether, our results suggest a paradoxical, facilitating impact of CF on procedural motor sequence learning. We propose that facilitated learning in the high-level fatigue condition stems from a reduction in the cognitive resources devoted to cognitive control processes that normally oppose automatic procedural acquisition mechanisms.
Sidarus, N., & Haggard, P. (2016). Difficult action decisions reduce the sense of agency: A study using the Eriksen flanker task. Acta Psychologica, 166, 1–11.
The sense of agency refers to the feeling that we are in control of our actions and, through them, of events in the outside world. Much research has focused on the importance of retrospectively matching predicted and actual action outcomes for a strong sense of agency. Yet, recent studies have revealed that a metacognitive signal about the fluency of action selection can prospectively inform our sense of agency. Fluent, or easy, action selection leads to a stronger sense of agency over action outcomes than dysfluent, or difficult, selection. Since these studies used subliminal priming to manipulate action selection, it remained unclear whether supraliminal stimuli affecting action selection would have similar effects.
We used supraliminal flankers to manipulate action selection in response to a central target. Experiment 1 revealed that conflict in action selection, induced by incongruent flankers and targets, led to reduced agency ratings over an outcome that followed the participant's response, relative to neutral and congruent flanking conditions. Experiment 2 replicated this result, and extended it to free choice between alternative actions. Finally, Experiment 3 varied the stimulus onset asynchrony (SOA) between flankers and target. Action selection performance varied with SOA. Agency ratings were always lower in incongruent than congruent trials, and this effect did not vary across SOAs. Sense of agency is influenced by a signal that tracks conflict in action selection, regardless of the visibility of stimuli inducing conflict, and even when the timing of the stimuli means that the conflict may not affect performance.
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.
Gabriel, R., Morais, J., & Kolinsky, R. (2016). A aprendizagem da leitura e suas implicações sobre a memória e a cognição. [Reading acquisition and its implications on memory and cognition]. Ilha do Desterro, 69(1), 61-78. DOI: http://dx.doi.org/10.5007/2175-8026.2016v69n1p61. Can learning to read change the information process and expand the storage capacity of the human brain? The purpose of this article is to review and to discuss models of memory (working memory, short term and long term memory) in their relation to language, as well as the possible cognitive changes prompted by literacy. By reviewing models of memory and executive functions, we aim at identifying questions that have promoted theoretical evolution, as well as the matching and disagreement in the concepts available in the area. Differences in knowledge processing and storage in literates and illiterates are highlighted, taking into account behavioral and brain imaging data. The data suggest that literacy alters the way in which linguistic knowledge is stored and processed by bursting the refinement of the visual and auditory perceptual systems, necessary to the grapheme-phoneme association.
Fernandes, T. & Kolinsky, R (Eds.) Special issue of Frontiers in Developmental Psychology, “The impact of learning to read on visual processing” . Also published as Frontiers ebook: Fernandes, T. & Kolinsky, R. (2016), Eds. “The impact of learning to read on visual processing”. Lausanne: Frontiers Media. doi: 10.3389/978-2-88919-716-3.
Reading is at the interface between the vision and spoken language domains. An emergent bulk of research indicates that learning to read strongly impacts on non-linguistic visual object processing, both at the behavioral level (e.g., on mirror image processing – enantiomorphy–) and at the brain level (e.g., inducing top-down effects as well as neural competition effects). Yet, many questions regarding the exact nature, locus, and consequences of these effects remain hitherto unanswered.
The current Special Topic aims at contributing to the understanding of how such a cultural activity as reading might modulate visual processing by providing a landmark forum in which researchers define the state of the art and future directions on this issue.
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.
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.
Caspar, E. Christensen, J.F., Cleeremans, A., & Haggard, P. (2016). Coercion changes the sense of agency in the human brain. Current Biology, 26, 1-8.
People may deny responsibility for negative conse- quences of their actions by claiming that they were ‘‘only obeying orders.’’ The ‘‘Nuremberg defense’’ of- fers one extreme example, though it is often dis- missed as merely an attempt to avoid responsibility. Milgram’s classic laboratory studies reported wide- spread obedience to an instruction to harm, suggest- ing that social coercion may alter mechanisms of voluntary agency, and hence abolish the normal experience of being in control of one’s own actions. However, Milgram’s and other studies relied on dissembling and on explicit measures of agency, which are known to be biased by social norms. Here, we combined coercive instructions to admin- ister harm to a co-participant, with implicit measures of sense of agency, based on perceived compres- sion of time intervals between voluntary actions and their outcomes, and with electrophysiological recordings. In two experiments, an experimenter ordered a volunteer to make a key-press action that caused either financial penalty or demonstrably painful electric shock to their co-participant, thereby increasing their own financial gain. Coercion increased the perceived interval between action and outcome, relative to a situation where partici- pants freely chose to inflict the same harms. Interest- ingly, coercion also reduced the neural processing of the outcomes of one’s own action. Thus, people who obey orders may subjectively experience their ac- tions as closer to passive movements than fully voluntary actions. Our results highlight the complex relation between the brain mechanisms that generate the subjective experience of voluntary ac- tions and social constructs, such as responsibility.