Linking perceptual learning with identical stimuli to imagery perceptual learning.

Perceptual learning is usually thought to be exclusively driven by the stimuli presented during training (and the underlying synaptic learning rules). In some way, we are slaves of our visual experiences. However, learning can occur even when no stimuli are presented at all. For example, Gabor contrast detection improves when only a blank screen is presented and observers are asked to imagine Gabor patches. Likewise, performance improves when observers are asked to imagine the nonexisting central line of a bisection stimulus to be offset either to the right or left. Hence, performance can improve without stimulus presentation. As shown in the auditory domain, performance can also improve when the very same stimulus is presented in all learning trials and observers were asked to discriminate differences which do not exist (observers were not told about the set up). Classic models of perceptual learning cannot handle these situations since they need proper stimulus presentation, i.e., variance in the stimuli, such as a left versus right offset in the bisection stimulus. Here, we show that perceptual learning with identical stimuli occurs in the visual domain, too. Second, we linked the two paradigms by telling observers that only the very same bisection stimulus was presented in all trials and asked them to imagine the central line to be offset either to the left or right. As in imagery learning, performance improved.

Remembering President Barack Obama's inauguration and the landing of US Airways Flight 1549: a comparison of the predictors of autobiographical and event memory.

We examined and compared the predictors of autobiographical memory (AM) consistency and event memory accuracy across two publicly documented yet disparate public events: the inauguration of Barack Obama as the 44th president of the United States on January 20th 2009, and the emergency landing of US Airways Flight 1549, off the coast of Manhattan, on January 15th 2009. We tracked autobiographical and event memories for both events, with assessments taking place within 2½ weeks of both events (Survey 1), and again between 3½ and 4 months after both events (Survey 2). In a series of stepwise regressions we found that the psychological variables of recalled emotional intensity and personal importance/centrality predicted AM consistency and event memory accuracy for the inauguration. Conversely, the rehearsal variables of covert rehearsal and media attention predicted, respectively, AM consistency and event memory accuracy for the plane landing. We conclude from these findings that different factors may underlie autobiographical and event memory for personally and culturally significant events (e.g., the inauguration), relative to noteworthy, yet less culturally significant, events (e.g., the plane landing).

Time course changes in corticospinal excitability during repetitive peripheral magnetic stimulation combined with motor imagery.

Repetitive peripheral magnetic stimulation (rPMS) induces proprioceptive afferents and facilitates corticospinal excitability. Short-term sessions of rPMS combined with motor imagery (MI) enhance corticospinal excitability more than rPMS alone. However, it is not clear how long the intervention of rPMS combined with MI would be needed to facilitate corticospinal excitability. Therefore, we investigated the time course change in corticospinal excitability during the combination of rPMS and MI. Thirteen healthy volunteers participated in a 20-min intervention under the following three experimental conditions on different days: rPMS, MI, and rPMS combined with MI (rPMS + MI). In the rPMS and rPMS + MI, the participants were delivered rPMS, which was 25 Hz, 2 s/train at 1.5 × of the train intensity induced muscle contractions, through the wrist extensor muscles. In the MI and rPMS + MI, the participants repeatedly imagined wrist movements for 2 s. Motor evoked potentials (MEPs) were recorded from the extensor carpi radialis (ECR) and flexor carpi radialis (FCR) muscles every 5 min for each condition. The MEP amplitudes of the ECR after > 10 min of intermittent rPMS combined with MI were greater than baseline. The MEP amplitude of the ECR in rPMS + MI was greater than that in rPMS condition after 20 min of intervention. The present results suggest that over 10 min of intermittent rPMS combined with MI facilitates corticospinal excitability, and that the effect of rPMS combined with MI on corticospinal excitability might be greater than that of rPMS alone.

[Internal reference frame for representation and storage of visual information during standing].

The participation of different afferent systems in organization of internal reference frame was studied. For this was chosen the task of visual comparison that executed in different experimental conditions: in upright standing, with inclined body or head in frontal plane and availability or non-availability visual information about external environment. Results showed that dominant orientation of referent stimulus (minimal value of mean error and minimal variability of responses) was connected with body position, mainly head position but not with gravity and visual vertical even when visual environment was available. It means that for creating the internal representing of vertical CNS mainly uses proprioceptive information about longitudinal axis of body.

Indirect modulation of human visual memory.

Conditions in which memories become maladaptive have inspired extensive research geared to modulate memory by targeting it directly and explicitly. Given limitations of direct memory modulation, we asked the following: can the target memories be modulated indirectly? To address this question, we uniquely targeted visual memories, and leveraged a paradigm utilizing instructions to either forget or remember newly encoded memories. We used a multi-domain approach, and applied the instructions to embedded verbal information presented during encoding (words), with the intention to indirectly modulate recognition of the target visual context memory itself (pictures). Accordingly, participants were presented with two lists of words, where each word was preceded and followed by pictures. Participants were instructed to either remember or forget the first list of words. As expected, the instruction to either remember or forget the words differentially influenced word memory strength. Importantly, the instruction regarding the words, indirectly modulated picture memory strength. Better memory for words resulted in reduced picture memory strength and vice versa, with the instruction to remember the words reducing picture memory strength. Together with a negative correlation between word and picture memory strength, the results suggest a competition for shared resources between memory for content and context. These findings may open new avenues to indirectly modulate maladaptive memories.

Visual field heterogeneity, laterality, and eidetic imagery in synesthesia.

JS was a grapheme-color synesthete in whom numerals and letters of the alphabet consistently evoked colors. In the first set of experiments we showed that the color - in a consistent and reliable manner - was most pronounced in the left visual field and in central vision. In the second experiment we devised a novel test for eidetic imagery and showed that his self-report of enhanced imagery could be verified experimentally. The implications of these findings for the level at which synesthesia occurs, the 'enhanced cross-activation' model, and the mechanisms of visual memory are discussed.

Common mechanisms of visual imagery and perception.

Detection of a visual target can be facilitated by flanking visual masks. A similar enhancement in detection thresholds was obtained when observers imagined the previously perceived masks. Imagery-induced facilitation was detected for as long as 5 minutes after observation of the masks by the targeted eye. These results indicated the existence of a low-level (monocular) memory that stores the sensory trace for several minutes and enables reactivation of early representations by higher processes. This memory, with its iconic nature, may subserve the interface between mental images and percepts.

Formation of cognitive structures in conditioned-reflex behavior in monkeys: Relationship with type of visual information.

The characteristics of learning processes and long-term memory (LTM) were studied in rhesus macaques discriminating visual stimuli (geometrical figures of different shapes, sizes, and orientations, and with different spatial relationships between image components). Trained monkeys were tested for the ability to perform invariant recognition after stimulus transformation, i.e., changes in size, shape, number of objects, and spatial relationships. Analysis of behavioral characteristics (correct solutions, refusals to decide, motor response times) revealed differences associated with the type of visual information. When monkeys discriminated between black and white geometrical figures of different shapes and orientations, as well as black-and-white figures with different shapes or orientations, the learning time was short and transformation of the stimuli had no effect on correct solutions: there was complete transfer of learning. When monkeys discriminated figures of different sizes or complex images with different spatial relationships, the learning time was significantly greater. Changes in the size and shape of figures led to significant reductions in correct solutions and significant increases in refusals to solve the task and in motor reaction times. Invariance of discrimination in this case appeared after additional training. The results obtained here showed that in conditioned reflex learning, the sensory processing of stimuli has the result that discriminatory features are formed in LTM, i.e., cognitive structures (functional neurophysiological mechanisms), these supporting the classification of visual images. The temporal conditioned link of the executive reaction is established with these. Their formation is determined by the type of sensory information and the existence in LTM of separate subsystems for spatial and non-spatial information.

Cueing color imagery: A critical analysis of imagery-perception congruency effects.

The relation between mental imagery and visual perception is a long debated topic in experimental psychology. In a recent study, Wantz, Borst, Mast, and Lobmaier (2015) demonstrated that color imagery could benefit color perception in a task that involved generating imagery in response to a cue prior to a forced-choice color discrimination task. Here, we scrutinized whether the method of Wantz et al. warrants strong inferences about the role of color imagery in color perception. In Experiments 1-3, we demonstrate that the imagery effect reported by Wantz et al. does replicate nicely using their method but does not occur when cue-target contingencies and a redundancy between the imagery and response dimensions are removed from their method. In Experiments 4-6, we explored cued imagery effects further using a method in which the cued imagery dimension was orthogonal to the response dimension. The results of these experiments demonstrate that a compelling endogenously cued imagery effect does not occur for lone targets but does occur for singleton color targets embedded amid homogenous color distractors. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Specifying the boundary conditions of the multimedia effect: The influence of content and its distribution between text and pictures.

It was investigated whether the beneficial effect of picture presentation might be influenced by the content conveyed through text and pictures and the way information is distributed between them. Ninety-nine students learnt in five between-subjects learning conditions (i.e., text with spatial contents plus pictures, text with visual contents plus pictures, only text with spatial contents, only text with visual contents, only picture) about a tourist centre and a holiday farm. Results showed that pictures (i.e., maps) were beneficial for learning if spatial knowledge had to be acquired, but did not support learning when non-spatial, visual knowledge had to be acquired. Furthermore, a high overlap of spatial information in text and picture was helpful, which can be explained by the assumption that learning is a text-guided process. On the other hand, regarding non-spatial visual information, a high text-picture overlap did not influence learning, probably because text alone was sufficient for acquiring visual knowledge. The implications of these findings are discussed.

Population response magnitude variation in inferotemporal cortex predicts image memorability.

Most accounts of image and object encoding in inferotemporal cortex (IT) focus on the distinct patterns of spikes that different images evoke across the IT population. By analyzing data collected from IT as monkeys performed a visual memory task, we demonstrate that variation in a complementary coding scheme, the magnitude of the population response, can largely account for how well images will be remembered. To investigate the origin of IT image memorability modulation, we probed convolutional neural network models trained to categorize objects. We found that, like the brain, different natural images evoked different magnitude responses from these networks, and in higher layers, larger magnitude responses were correlated with the images that humans and monkeys find most memorable. Together, these results suggest that variation in IT population response magnitude is a natural consequence of the optimizations required for visual processing, and that this variation has consequences for visual memory.

Learning basic surgical skills with mental imagery: using the simulation centre in the mind.

CONTEXT: Although surgeons and athletes frequently use mental imagery in preparing to perform, mental imagery has not been extensively researched as a learning technique in medical education. OBJECTIVE: A mental imagery rehearsal technique was experimentally compared with textbook study to determine the effects of each on the learning of basic surgical skills. METHODS: Sixty-four Year 2 medical students were randomly assigned to 2 treatment groups in which they undertook either mental imagery or textbook study. Both groups received the usual skills course of didactic lectures, demonstrations, physical practice with pigs' feet and a live animal laboratory. One group received additional training in mental imagery and the other group was given textbook study. Performance was assessed at 3 different time-points using a reliable rating scale. RESULTS: Analysis of variance on student performance in live rabbit surgery revealed a significant interaction favouring the imagery group over the textbook study group. CONCLUSIONS: The mental imagery technique appeared to transfer learning from practice to actual surgery better than textbook study.

Face imagery is based on featural representations.

The effect of imagery on featural and configural face processing was investigated using blurred and scrambled faces. By means of blurring, featural information is reduced; by scrambling a face into its constituent parts configural information is lost. Twenty-four participants learned ten faces together with the sound of a name. In following matching-to-sample tasks participants had to decide whether an auditory presented name belonged to a visually presented scrambled or blurred face in two experimental conditions. In the imagery condition, the name was presented prior to the visual stimulus and participants were required to imagine the corresponding face as clearly and vividly as possible. In the perception condition name and test face were presented simultaneously, thus no facilitation via mental imagery was possible. Analyses of the hit values showed that in the imagery condition scrambled faces were recognized significantly better than blurred faces whereas there was no such effect for the perception condition. The results suggest that mental imagery activates featural representations more than configural representations.

Dual-task interference is greater in delayed grasping than in visually guided grasping.

Previous kinematic research suggests that visually guided grasping employs an accurate real-time control system in the dorsal stream, whereas delayed grasping relies on less accurate stored information derived by the perceptual system in the ventral stream. We explored these ideas in two experiments combining visually guided and delayed grasping with auditory tasks involving perception-based imagery and semantic memory. In both experiments, participants were cued to grasp three-dimensional objects of varying sizes. During visually guided trials, objects were visible during the interval between the cue and movement onset. During delayed trials, objects were occluded at the time of the cue. In Experiment 1, the second task required participants to listen to object names and vocally respond if the objects were of a particular shape. In Experiment 2, participants studied a paired-associates list prior to testing and then performed cued recall while grasping. The results of these experiments showed that there was reciprocal interference on both tasks, which was consistently greater during delayed grasping. Experiment 2 showed that the introduction of the second task resulted in larger grip apertures during delayed grasping. This supports the idea that delayed grasping involves processing of stored perception-based information that shares resources with cross-modal tasks involving imagery and memory.

Visual imagery and visual representation.

Among many controversies in visual neuroscience is whether visual imagery of objects, scenes and living beings is based upon contributions of the early visual areas or depends on hierarchical higher visual areas only, and whether the cortical areas subserving visual imagery are identical to those underlying visual perception. These questions are important for furthering our understanding of vision, since areas active in visual imagery might tell us how the visual cortex represents objects, scenes and living beings. Here, P.E. Roland and B. Gulyás present their hypothesis, based on experimental evidence in man and primates, that the visual areas subserving visual imagery are parieto-occipital and temporo-occipital visual association areas, and that these areas form only a subset of the visual areas engaged in perception. This hypothesis is consistent with the view that objects, scenes and living beings are represented, stored and re-evoked outside the domain of the primary visual cortex and its immediate neighbours.

Overgeneral memory extends to pictorial retrieval cues and correlates with cognitive features in posttraumatic stress disorder.

Individuals with posttraumatic stress disorder (PTSD) show overgeneral memory (OGM) when retrieving autobiographical memories to word cues. We investigated whether OGM extends to picture cues and whether it is related to PTSD symptoms and cognitions. Trauma survivors with (n = 29) and without (n = 26) PTSD completed the standard Autobiographical Memory Test (AMT) and a novel picture version. Compared to the no-PTSD group, the PTSD group showed OGM in both test versions. Pictures facilitated specific memory retrieval, but this effect was no longer significant when verbal intelligence or depressive symptoms were controlled. OGM correlated with PTSD symptoms and perceived self-change; with intrusive memories, their perceived "nowness," responses to intrusions (thought suppression, rumination, dissociation), and negative interpretations of symptoms.

Limited capacity for contour curvature in iconic memory.

We measured the difference threshold for contour curvature in iconic memory by using the cued discrimination method. The study stimulus consisting of 2 to 6 curved contours was briefly presented in the fovea, followed by two lines as cues. Subjects discriminated the curvature of two cued curves. The cue delays were 0 msec. and 300 msec. in Exps. 1 and 2, respectively, and 50 msec. before the study offset in Exp. 3. Analysis of data from Exps. 1 and 2 showed that the Weber fraction rose monotonically with the increase in set size. Clear set-size effects indicate that iconic memory has a limited capacity. Moreover, clear set-size effect in Exp. 3 indicates that perception itself has a limited capacity. Larger set-size effects in Exp. 1 than in Exp. 3 suggest that iconic memory after perceptual process has limited capacity. These properties of iconic memory at threshold level are contradictory to the traditional view that iconic memory has a high capacity both at suprathreshold and categorical levels.

Mutual information-based feature selection for low-cost BCIs based on motor imagery.

In the present study a feature selection algorithm based on mutual information (MI) was applied to electro-encephalographic (EEG) data acquired during three different motor imagery tasks from two dataset: Dataset I from BCI Competition IV including full scalp recordings from four subjects, and new data recorded from three subjects using the popular low-cost Emotiv EPOC EEG headset. The aim was to evaluate optimal channels and band-power (BP) features for motor imagery tasks discrimination, in order to assess the feasibility of a portable low-cost motor imagery based Brain-Computer Interface (BCI) system. The minimal sub set of features most relevant to task description and less redundant to each other was determined, and the corresponding classification accuracy was assessed offline employing linear support vector machine (SVM) in a 10-fold cross validation scheme. The analysis was performed: (a) on the original full Dataset I from BCI competition IV, (b) on a restricted channels set from Dataset I corresponding to available Emotiv EPOC electrodes locations, and (c) on data recorded with the EPOC system. Results from (a) showed that an offline classification accuracy above 80% can be reached using only 5 features. Limiting the analysis to EPOC channels caused a decrease of classification accuracy, although it still remained above chance level, both for data from (b) and (c). A top accuracy of 70% was achieved using 2 optimal features. These results encourage further research towards the development of portable low cost motor imagery-based BCI systems.

La teoría del sueño de F. S. Perls: evolución, problemas teóricos y prácticos / F. S. Perls's dream theory: evolution, theoretical and practical problems / A teoria do sonho de F. S. perls: evolução, problemas teóricos e práticos

La teoría del sueño creada por F. S. Perls, tradicionalmente, ha sido caracterizada como una proyección o un mensaje existencial. Sin embargo, esta descripción sólo representa una explicación simplista de la conceptualización más amplia y original del fenómeno onírico desarrollada por Perls. En este sentido, en el presente escrito se hace una exposición ordenada de la teoría perlsiana del sueño, así como un análisis crítico de las proposiciones en las cuales se fundamenta, prestando especial atención a los errores inherentes en ésta y sus implicaciones en la práctica clínica. Se concluye que la teoría perlsiana de lo onírico evolucionó en tres etapas, a saber, modelo original del sueño, modelo de correspondencia y modelo clásico del sueño, cada uno de los cuales constituye, por derecho propio, una teoría del sueño en la cual se define el fenómeno onírico de una manera particular y se le atribuyen funciones psicológicas y terapéuticas concretas, al igual que una metodología de trabajo específica.

The dream theory created by F. S. Perls, traditionally, has been characterized as a projection or an existential message. However, this description only represents a simplistic explanation of the broader and original conceptualization of the dream phenomenon developed by Perls. In this regard, in this paper an orderly exposition of the perlsian theory of the dream is done, as well as a critical analysis of the propositions on which it is based, paying special attention to the errors inherent in it and its implications in clinical practice. It is concluded that the perlsian theory of the oneiric evolved in three stages, namely, original model of the dream, model of correspondence and classical model of the dream, each of which constitutes, in its own right, a theory of the dream in which it defines the dream phenomenon in a particular way and is attributed to specific psychological and therapeutic functions, as well as a specific work methodology.

A teoria sobre sonhos criada por F. S. Perls tem sido tradicionalmente caracterizada como uma projeção ou uma mensagem existencial. No entanto, esta descrição representa apenas uma explicação simplista da conceituação mais ampla e original do fenômeno onírico desenvolvida por Perls. Este artigo apresenta uma exposição ordenada da teoria perlsiana do sonho e uma análise crítica de seus pressupostos, com especial atenção para os erros inerentes a ela e suas implicações na prática clínica. Conclui-se que a teoria perlsiana dos sonhos evoluiu em três fases a saber, a) modelo original do sonho, b) modelo de correspondência, e c) modelo clássico de sono. Cada um desses modelos constitui-se de forma própria como uma teoria específica sobre sonhos na qual define o fenômeno onírico de uma maneira particular e lhe são atribuídos funções psicológicas e terapêuticas concretas, bem como uma metodologia de trabalho específica.