Opponent colours induced by rotating discs

We found a novel visual illusion by using a rotating disc that has some coloured sectors with black arcs. When this disc rotates, illusory colours are seen in the concentric rings that are created by the rotating arcs. The illusory colours are the opponent colours of the sectors that the corresponding arcs are in. Even though we could not differentiate the colours of the individual sectors when the disc rotated quickly, the illusory colours that were the opponent colours of the sector colours could be seen. This visual illusion thus suggests that our visual system can process visual stimuli that we cannot perceive as colours.     

Pigeons perceive the Ebbinghaus-Titchener circles as an assimilation illusion

A target circle surrounded by larger "inducer" circles looks smaller, and one surrounded by smaller circles looks larger than they really are. This is the Ebbinghaus-Titchener illusion, which remains one of the strongest and most robust of contrast illusions. Although there have been many studies on this illusion in humans, virtually none have addressed how nonhuman animals perceive the same figures. Here the authors show that the Ebbinghaus-Titchener figures also induce a strong illusion in pigeons but, surprisingly, in the other direction; that is, all five successfully trained pigeons judged the target circle surrounded by larger circles to be larger than it really is and vice versa. Further analyses proved that neither the gaps between target and inducer circles nor the cumulative weighted surface of these figural elements could account for the birds' responses. Pigeons are known to show similarities to humans on various cognitive and perceptual tasks including concept formation, short-term memory, and some visual illusions. Our results, taken together with pigeons' previously demonstrated failure at visual completion, provide strong evidence that pigeons may actually experience a visual world too different for us to imagine.     

Pigeons (Columba livia) plan future moves on computerized maze tasks

Planning, the internal process of formulating an organized method about one's future behavior, should be advantageous for non-human animals as well as for humans. However, little is known about this process in avian species. We examined planning processes in pigeons (Columba livia) using a computerized maze task. In Experiment 1, we found that the pigeons plan their next one step, and in some cases even correctly adjust their actions after change of goal locations, while performing on a plus-shaped maze. We also showed that the pigeons might even plan two steps on familiar, well-practiced mazes. In Experiment 2, we discovered that the subjects plan the direction they would go first before starting to solve a four-arm shuriken (a Japanese traditional throwing knife)-shaped maze. The birds also corrected their previously planned actions after change of goal locations. Our results from these experiments suggest that planning ahead is within the cognitive capacity of a "bird brain", and that it may be more widespread in the animal kingdom than has been presumed.     

You say tomato? Collaborative remembering leads to more false memories for intimate couples than for strangers

Research on memory conformity shows that collaborative remembering--typically in the form of discussion--can influence people's memories. One question that remains is whether it matters with whom we discuss our memories. To address this question we compared people's memories for an event after they discussed that event with either their romantic partner or a stranger. Pairs of subjects watched slightly different versions of a movie, and then discussed some details from the movie, but not others. Subjects were better at remembering non-discussed details than discussed details: when remembering discussed details they incorrectly reported information from their partner's version instead of their own. In addition, subjects who discussed the event with their romantic partner (rather than with a stranger) were even more likely to report false memories. We discuss our findings in relation to other research on memory conformity, social influences on false memories, and memory systems within romantic relationships.     

The occurrence of the filled duration illusion: A comparison of the method of adjustment with the method of magnitude estimation

A time interval between the onset and the offset of a continuous sound (filled interval) is often perceived to be longer than a time interval between two successive brief sounds (empty interval) of the same physical duration. The present study examined whether and how this phenomenon, sometimes called the filled duration illusion (FDI), occurs for short time intervals (40–520 ms). The investigation was conducted with the method of adjustment (Experiment 1) and the method of magnitude estimation (Experiment 2). When the method of adjustment was used, the FDI did not appear for the majority of the participants, but it appeared clearly for some participants. In the latter case, the amount of the FDI increased as the interval duration lengthened. The FDI was more likely to occur with magnitude estimation than with the method of adjustment. The participants who showed clear FDI with one method did not necessarily show such clear FDI with the other method.     

A reversed Ebbinghaus–Titchener illusion in bantams (Gallus gallus domesticus)

A disk surrounded by smaller disks looks larger, and one surrounded by larger disks looks smaller than reality. This visual illusion, called the Ebbinghaus–Titchener illusion, remains one of the strongest and most robust illusions induced by contrast with the surrounding stimuli in humans. In the present study, we asked whether bantams would perceive this illusion. We trained three bantams to classify six diameters of target disks surrounded by inducer disks of a constant diameter into “small” or “large”. In the test that followed, the diameters of the inducer disks were systematically changed. The results showed that the Ebbinghaus–Titchener figures also induce a strong illusion in bantams, but in the other direction, that is, bantams perceive a target disk surrounded by smaller disks to be smaller than it really is and vice versa. Possible confounding factors, such as the gap between target disk and inducer disks and the weighted sum of surface of these figural elements, could not account for the subjects’ biased responses. Taken together with the pigeon study by Nakamura et al. (J Exp Psychol Anim Behav Process 34:375–387 2008), these results show that bantams as well as pigeons perceive an illusion induced by assimilation effects, not by contrast ones, for the Ebbinghaus–Titchener types of illusory figures. Perhaps perceptual processes underlying such illusory perception (i.e., lack of contrast effects) shown in bantams and pigeons may be partly shared among other avian species.     

Does Mealtime Communication Improve Happiness? Considering the Trait of Shyness1

Shared mealtimes have been found to be important daily rituals with positive effects on behavior and mental health, such as increasing subjective well-being. However, most previous studies have not considered possible barriers to these positive effects, specifically shyness. We investigated the relationships among shared mealtime quality, shyness, and subjective well-being, and the moderating role of shyness in the relationship between the other two variables by surveying a sample of college students (n = 305). Correlational analyses revealed that shared mealtime quality was negatively associated with shyness and positively associated with subjective well-being. Hierarchical regression analyses revealed that shared mealtime quality was significantly associated with subjective well-being, as was the interaction between the friend factor of shared mealtime quality and shyness. Therefore, shared mealtime quality might help improve happiness, but shyness should be considered a possible barrier to this beneficial effect when meals are shared with friends.     

Production of regular rhythm induced by external stimuli in rats

Animal Cognition - Rhythmic ability is important for locomotion, communication, and coordination between group members during the daily life of animals. We aimed to examine the rhythm perception...     

Sensory Processing Sensitivity Moderates the Relationships Between Life Skills and Depressive Tendencies in University Students1

University students often experience depressive symptoms, and strengthening of life skills may be beneficial for improving their mental health. Several studies have suggested that life skills effective in reducing depressive tendencies vary by individuals depending on differences in sensory processing sensitivity (SPS). SPS is a genetically determined trait characterized by sensitivity and reactivity to environmental stimuli. This study investigated the relationship between life skills and depressive tendencies based on individual differences in SPS. A total of 868 Japanese university students (mean age = 19.8 years, SD = 1.3 years) completed a questionnaire measuring levels of SPS—decision-making, interpersonal relationships, effective communication, and emotional coping skills—and depressive tendencies. Hierarchical multiple regression and simple slopes analyses indicated that interpersonal relationship skills were negatively correlated with depression regardless of SPS levels. Furthermore, decision-making skills were negatively correlated with depressive tendencies only in low-SPS students. Emotional coping skills were negatively correlated with depressive tendencies in high-SPS students. These results may help universities incorporate SPS levels when creating life-skills-based interventions for students.     

Pigeons (Columba livia) integrate visual motion using the vector average rule: effect of viewing distance

Animal Cognition - Integrating local motion signals detected by the primary motion detector is crucial for representing a rigid, two-dimensional motion. The nature of motion integration has been...