Orientation-contingent color aftereffects mediated by subjective transparent structures

We examined whether the orientation-contingent color aftereffect (the McCollough effect) could be mediated by subjective horizontal and vertical structure induced by the perception of transparency. In our experiments, red vertical bars and green horizontal bars were alternated as an adapting stimulus. After adaptation, subjects (n=6) were asked to adjust the green and red saturation of a test pattern until they obtained a neutral gray. Horizontal and vertical stripes were combined in the test pattern in three different ways: (1) overlapping with a luminance combination that gave rise to a perception of transparent overlays of horizontal and vertical stripes (valid transparency condition), (2) overlapping with luminance combinations that did not induce a perception of transparency (invalid transparency condition) and that appeased more as a patchwork of checks, and (3) presented in adjacent, nonoverlapping areas. Our results showed that the McCollough effect was significantly greater in the valid transparency condition than in the invalid transparency conditions. The effect in the valid transparency condition was nevertheless less strong than was the effect seen with the standard test stimulus made up of nonoverlapping vertical and horizontal stripes, Our results suggest that the McCollough effect can be mediated by the subjective spatial organization (inner representation of vertical and horizontal stripes) that accompanies the perception of transparency in our stimulus.     

A unified model for perceptual learning

Perceptual learning in adult humans and animals refers to improvements in sensory abilities after training. These improvements had been thought to occur only when attention is focused on the stimuli to be learned (task-relevant learning) but recent studies demonstrate performance improvements outside the focus of attention (task-irrelevant learning). Here, we propose a unified model that explains both task-relevant and task-irrelevant learning. The model suggests that long-term sensitivity enhancements to task-relevant or irrelevant stimuli occur as a result of timely interactions between diffused signals triggered by task performance and signals produced by stimulus presentation. The proposed mechanism uses multiple attentional and reinforcement systems that rely on different underlying neuromodulators. Our model provides insights into how neural modulators, attentional and reinforcement learning systems are related.     

Influences of environmental context on the recency effect in free recall

A total of 208 undergraduate participants incidentally encoded a list of seven pairs of familiar words in two experiments. A 30-sec calculation task was imposed before and after each pair was encoded. Participants received a free recall test 24 h (Experiment 1) or 10 min (Experiment 2) after the encoding session, under conditions in which the original environmental context was reinstated or not. The environmental context was manipulated in terms of the combination of the physical features of the room, the subsidiary task conducted, the experimenter (Experiment 1), or background music (Experiment 2). A recency effect appeared when the original environmental context was reinstated in both experiments, even though the IPI/RI ratio was too small to produce recency effects according to the ratio rule. The results imply that the environmental context should be taken into account for the recency effect.     

Effects of environmental context manipulated by the combination of place and task on free recall

Three experiments, using a 2 (study context) × 2 (test context) between‐subjects design, were conducted to examine the effects of environmental context manipulated by the combination of two contextual elements, place and task, on free recall. Undergraduates individually studied nouns and received a free‐recall test, with a 10‐minute filled retention interval. The contexts were manipulated by the combination of task and place in Experiment 1, by place alone in Experiment 2, and by task alone in Experiment 3. For the manipulation of place and task, two perceptually distinctive places and two distinctive tasks (a calculation task and a fine‐motor task) were used. Tasks were imposed before and after studying target items and before a free‐recall test. Significant environmental‐context effects were yielded in Experiment 1, but not in the other experiments. The implications of the results are discussed.     

Multisensory perceptual learning reshapes both fast and slow mechanisms of crossmodal processing

Previous research has shown that sounds facilitate perception of visual patterns appearing immediately after the sound but impair perception of patterns appearing after some delay. Here we examined the spatial gradient of the fast crossmodal facilitation effect and the slow inhibition effect in order to test whether they reflect separate mechanisms. We found that crossmodal facilitation is only observed at visual field locations overlapping with the sound, whereas crossmodal inhibition affects the whole hemifield. Furthermore, we tested whether multisensory perceptual learning with misaligned audio-visual stimuli reshapes crossmodal facilitation and inhibition. We found that training shifts crossmodal facilitation towards the trained location without changing its range. By contrast, training narrows the range of inhibition without shifting its position. Our results suggest that crossmodal facilitation and inhibition reflect separate mechanisms that can both be reshaped by multisensory experience even in adult humans. Multisensory links seem to be more plastic than previously thought.     

Study-time effect on free recall within and out of context

Three experiments examined whether or not the study-time effect, which was observed when recall took place in the original environmental context, was eliminated or markedly diminished when recall took place in a different environmental context. A total of 456 undergraduates studied a list of words for either a short or long study time before receiving an oral free recall test under conditions where the original environmental context was or was not reinstated. Environmental context was manipulated by the combination of physical features of the room, subsidiary task, and experimenter. Inter-item association was minimised in Experiment 1, and free recall performance was measured independently of inter-item association in Experiments 2 and 3. The results were: (1) a greater study-time effect was found when the original context was reinstated than when it was not reinstated, and (2) the study-time effect disappeared when neither contextual nor inter-item associative cues were available. The results suggest that environmental context is involved in the production of the study-time effect.     

Task-dependent changes of the psychophysical motion-tuning functions in the course of perceptual learning

In some cases, perceptual learning is task-specific. However, task-dependent effects of perceptual learning on psychophysical motion-tuning functions have yet to be clarified. In the present study, subjects performed motion detection or discrimination of the same stimulus over the course of four sessions held on separate days. Subjects who performed motion detection showed the most highly improved performance on the trained motion directions. However, after discrimination training, the highest improvement was not observed at the trained directions but shifted away from them. These results can be explained by lateral inhibition. Task demands may differentially modulate excitatory and inhibitory signals to directions in the vicinity of the trained directions.     

Alexithymia is not related to tolerance for cold pressor pain

To test the hypothesis that higher scores on alexithymia are associated with reduced tolerance for cold pressor pain, 116 college undergraduates completed the Toronto Alexithymia Scale-20 of Bagby, Parker and Taylor and engaged in the cold pressor test. Their alexithymia scores were not associated with tolerance for cold pressor pain, suggesting that individuals scoring high on alexithymia do not show a general hypersensitivity to a cold stimulus.     

Optimism and Longevity Among Japanese Older Adults

Journal of Happiness Studies - Optimism has been linked to better physical health across various outcomes, including greater longevity. However, most evidence is from Western populations, leaving...