In Experiment 1, undergraduates first made choices hypothetically between an uncertain large reward and a certain small reward, second they made choices with real money, and finally they again made hypothetical choices. The discounting rates in the first hypothetical reward condition were higher than those in the following conditions of real or hypothetical rewards. A significant difference in the discounting rate across conditions was not found when the real reward condition was replaced by the hypothetical reward condition (Experiment 2) or by the condition with probability contingency and hypothetical reward (Experiment 3). The difference in the discounting rate was replicated between the hypothetical and real reward conditions when the participants invested money when they selected an uncertain-large reward (Experiment 4). Johnson & Bickel (2002) found no difference in the discounting rate between hypothetical and real rewards when the real rewards were delivered to participants not during but after the experiment. The present experiments, by contrast, delivered real money immediately after every choice, and demonstrate that real and hypothetical rewards differ in the values of discounting rates.
A recent study proposed that saccade trajectories often curve away from previously fixated locations during visual search because of the inhibitory mechanism which prevents inefficient reexamination of rejected distractors. In the present study, we examined whether visual contexts influence saccade trajectories as is the case with other inhibitory effects in visual search (e. g., inhibition of return). Computer-generated natural scenes were used as search stimuli and participants were required to look for a toy car in the scene. The results showed that the saccade trajectories were affected by at least three previous fixations and the effect decreased exponentially with the number of intervening fixations. These results are consistent with the findings in the previous study using abstract stimuli (the O among Cs search task). The relationships between saccade curvature and other inhibitory effects in visual search are discussed.
Visual context, such as an association between a target location and a distractor configuration, has been shown to be implicitly learned through repeated experiences in a visual search task, and facilitates the search performance (contextual cueing effect). In the present study, we examined whether the whole layout or only the local half-layout contributed to contextual cueing. In a training session, the whole layout or the local half-layout including the target location was repeated. Then in a test session, half of the layout including the target location was presented while the remaining half of the layout was randomly changed. The results showed that the search performance in the repeated whole layout condition was equivalent to the condition where only half of the layout was repeated throughout both the training and the test sessions. This suggests that the local layout around the target location was selectively learned and used for contextual cueing even if the whole layout was repeated.
In the Deese-Roediger-McDermott (DRM) procedure, false recall of a word that was not presented (the critical-lure) can be produced when participants study a list of associative words related to the critical-lure. Recently, some studies using the DRM procedure showed that young children did not produce false recall. The present study hypothesized that the children did not produce false recall in those studies because the lists of words did not reflect the children's associative knowledge. To test this possibility, the present study developed lists that reflect the associative knowledge of five-year-old children and examined false recall using the DRM procedure. The results showed that children falsely recalled the critical-lure after studying the lists that reflected the children's associative knowledge, while they did not recall the critical-lure after studying the lists that reflected adults' associative knowledge. The results indicate that children produce false recall when the lists of words reflect those children's associative knowledge. The present finding suggests that the structuring of semantic knowledge that mediates false recall of the critical-lure has developed five years of age.
Simultaneity is important in cross-modal information processing. However, it is still unclear how simultaneity is perceived between different sensory modalities. Various factors such as spatial location or attention are known to affect simultaneity judgments. In the present study, we focused on the simultaneity judgments of dynamic events, and investigated what kinds of dynamic properties affect these judgments. We presented the deformation of a virtual object in vision and haptics with various stimulus onset asynchronies. Participants judged whether the deformation occurred simultaneously. We measured the effects of duration, velocity, and the amount of deformation on the visual-haptic simultaneity judgments. The results showed that the point of subjective simultaneity changed depending on the duration of deformation. For a shorter duration (400ms), the visual deformation needed to precede the haptic one to be judged as simultaneous, while for a longer duration (800ms, 1200ms), the asymmetry was diminished, suggesting that information relevant to the duration of the event was used for the vision-haptics simultaneity judgments of dynamic events.