Absence Of Explicit Knowledge Research Articles

Interleaved practice benefits implicit sequence learning and transfer

Compared to blocked practice, interleaved practice of different tasks leads to superior long-term retention despite poorer initial acquisition performance. This phenomenon, the contextual interference effect, is well documented in various domains but it is not yet clear if it persists in the absence of explicit knowledge in terms of fine motor sequence learning. Additionally, while there is some evidence that interleaved practice leads to improved transfer of learning to similar actions, transfer of implicit motor sequence learning has not been explored. The present studies used a serial reaction time task where participants practiced three different eight-item sequences that were either interleaved or blocked on Day 1 (training) and Day 2 (testing). In Experiment 1, the retention of the three training sequences was tested on Day 2 and in Experiment 2, three novel sequences were performed on Day 2 to measure transfer. We assessed whether subjects were aware of the sequences to determine whether the benefit of interleaved practice extends to implicitly learned sequences. Even for participants who reported no awareness of the sequences, interleaving led to a benefit for both retention and transfer compared to participants who practiced blocked sequences. Those who trained with blocked sequences were left unprepared for interleaved sequences at test, while those who trained with interleaved sequences were unaffected by testing condition, revealing that learning resulting from blocked practice may be less flexible and more vulnerable to testing conditions. These results indicate that the benefit of interleaved practice extends to implicit motor sequence learning and transfer.

Agreeing to Disagree: Deaf and Hearing Children's Awareness of Subject–Verb Number Agreement

This study investigated deaf adolescents' implicit and explicit awareness of subject-verb number agreement. In Experiment 1, a self-paced reading task, the reading times of deaf and hearing children (matched for reading and chronological age, mean=8;3 and 13;10 years) increased when sentences contained disagreeing subject-verb number markers. However, deaf adolescents' slowing occurred later in the sentence than it did in both groups of hearing children. The same deaf adolescents were unable to detect and correct subject-verb agreement errors in Experiment 2, whereas both groups of hearing children performed well on this task. Thus, deaf adolescents demonstrated implicit awareness of agreement in the absence of explicit knowledge. Moreover, this nascent awareness was below that expected on the basis of their (substantially delayed) reading ability. Therefore, grammatical difficulties could be a significant impediment to deaf children's literacy. Future research should examine whether this is a result of late or incomplete learning of English, bilingualism, or another factor.

Consciousness Meets Neuroeconomics: What Is the Value of Stimulus Awareness in Decision Making?

An important question in neuroeconomics is how consciousness affects decision making. In this issue of Neuron, Pessiglione et al. take an initial step toward addressing this question by showing that humans learn to make optimal choices in the absence of explicit knowledge about key parameters of the decision-making problem.

Human Amygdala Sensitivity to the Pupil Size of Others

Stimulation of the amygdala produces pupil dilation in animal and human subjects. The present study examined whether the amygdala is sensitive to variations in the pupil size of others. Male subjects underwent event-related functional magnetic resonance imaging while passively viewing unfamiliar female faces whose pupils were either unaltered (natural variations in large and small pupils) or altered to be larger or smaller than their original size. Results revealed that the right amygdala and left amygdala/substantia innominata were sensitive to the pupil size of others, exhibiting increased activity for faces with relatively large pupils. Upon debrief, no subject reported being aware that the pupils had been manipulated. These results suggest a function for the amygdala in the detection of changes in pupil size, an index of arousal and/or interest on the part of a conspecific, even in the absence of explicit knowledge.

Masked Presentations of Emotional Facial Expressions Modulate Amygdala Activity without Explicit Knowledge

Functional magnetic resonance imaging (fMRI) of the human brain was used to study whether the amygdala is activated in response to emotional stimuli, even in the absence of explicit knowledge that such stimuli were presented. Pictures of human faces bearing fearful or happy expressions were presented to 10 normal, healthy subjects by using a backward masking procedure that resulted in 8 of 10 subjects reporting that they had not seen these facial expressions. The backward masking procedure consisted of 33 msec presentations of fearful or happy facial expressions, their offset coincident with the onset of 167 msec presentations of neutral facial expressions. Although subjects reported seeing only neutral faces, blood oxygen level-dependent (BOLD) fMRI signal in the amygdala was significantly higher during viewing of masked fearful faces than during the viewing of masked happy faces. This difference was composed of significant signal increases in the amygdala to masked fearful faces as well as significant signal decreases to masked happy faces, consistent with the notion that the level of amygdala activation is affected differentially by the emotional valence of external stimuli. In addition, these facial expressions activated the sublenticular substantia innominata (SI), where signal increases were observed to both fearful and happy faces--suggesting a spatial dissociation of territories that respond to emotional valence versus salience or arousal value. This study, using fMRI in conjunction with masked stimulus presentations, represents an initial step toward determining the role of the amygdala in nonconscious processing.

Implicit learning and tacit knowledge: an essay on the cognitive unconscious

In this new volume in the Oxford Psychology Series, the author presents a highly readable account of the cognitive unconscious, focusing in particular on the problem of learning. Implicit is defined as the acquisition of knowledge that takes place independently of the conscious attempts to learn and largely in the absence of explicit knowledge about what was acquired. One of the core assumptions of this argument is that is a fundamental, root process, one that lies at the very heart of the adaptive behavioral repertoire of every complex organism. The author's goals are to outline the essential features of that have emerged from the many studies that have been carried out in a variety of experimental laboratories over the past several decades; to present the various alternative perspectives on this issue that have been proposed by other researchers and to try to accommodate these views with his own; to structure the literature so that it can be seen in the context of standard heuristics of evolutionary biology; to present the material within a functionalist approach and to try to show why the experimental data should be seen as entailing particular epistemological perspectives; and to present processing as encompassing a general and ubiquitous set of operations that have wide currency and several possible applications. Chapter 1 begins with the core problem under consideration in this book, a characterization of implicit learning as it has come to be used in the literature. Reber puts this seemingly specialized topic into a general framework and suggests a theoretical model based on standard heuristics of evolutionary biology. In his account, Reber weaves a capsule history of interest in and work on the cognitive unconscious. Chapter 2 turns to a detailed overview of the experimental work on the acquisition of knowledge, which currently is of great interest. Chapter 3 develops the evolutionary model within which one can see and cognition as richly intertwining issues and not as two distinct fields with one dominating the other. Finally, Chapter 4 explores a variety of entailments and speculations concerning cognitive processes and their general role in the larger scope of human performance