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...     

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...     

Asymmetrical drawing patterns on the temples by left-handers

Twenty-three Japanese genuine left-handers were selected by a Laterality Quotient scale and asked to draw the letter S on their own temples and foreheads. The way they drew on the temples showed an asymmetry that was the mirror reversal of that of right-handers, as found in a previous study. Left-handers drew a reversed letter S on their right temple much more often than on the left temple, whereas right-handers drew them in reverse more often on the left temple. They also drew it in reverse on the forehead irrespective of their handedness.     

Capuchin monkeys (<Emphasis Type="Italic">Cebus apella</Emphasis>) use conspecifics’ emotional expressions to evaluate emotional valence of objects

Emotional expressions provide important clues to other individuals’ emotional states, as well as the environmental situations leading to such states. Although monkeys often modify their behavior in response to others’ expressions, it is unclear whether this reflects understanding of emotional meanings of expressions, or simpler, non-cognitive processes. The present study investigated whether a New World monkey species, tufted capuchin monkeys, recognize objects as elicitors of others’ expressions. Observer monkeys witnessed another individual (demonstrator) reacting either positively or negatively to the contents of one of two containers and were then allowed to choose one of the containers. The observer preferred the container that evoked positive expressions in the demonstrator and avoided the container that evoked negative expressions. Thus, the monkeys appropriately associated the emotional valence of others’ expressions with the container. This finding supports the view that the ability to represent others’ emotions is not limited to humans and apes.     

Ab initio pseudopotential studies on an Al Σ = 9 grain boundary: Effects of Na and Ca impurities

The electronic properties of an Al = 9 tilt grain boundary with segregated Na and Ca impurity atoms have been calculated by a first-principles pseudopotential method. The results show that the boundary expands and the charge density decreases significantly over the whole boundary by the segregation of Na and Ca, and there are no stronger bonds than those associated with metallic bonding in the boundary even with the impurities. It is concluded that the embrittlement promotion mechanism by Na or Ca segregation in the Al boundaries is one kind of 'decohesion model'.     

Suppressed semantic information accelerates analytic problem solving

The present study investigated the limits of semantic processing without awareness, during continuous flash suppression (CFS). We used compound remote associate word problems, in which three seemingly unrelated words (e.g., pine, crab, sauce) form a common compound with a single solution word (e.g., apple). During the first 3 s of each trial, the three problem words or three irrelevant words (control condition) were suppressed from awareness, using CFS. The words then became visible, and participants attempted to solve the word problem. Once the participants solved the problem, they indicated whether they had solved it by insight or analytically. Overall, the compound remote associate word problems were solved significantly faster after the problem words, as compared with irrelevant words, were presented during the suppression period. However this facilitation occurred only when people solved with analysis, not with insight. These results demonstrate that semantic processing, but not necessarily semantic integration, may occur without awareness.     

Comparing the effects of implicit and explicit temporal expectation on choice response time and response conflict

People can use temporally structured sensory information to anticipate future events. Temporal information can be presented implicitly through probability manipulation without participants’ awareness of the manipulation, or explicitly conveyed through instructions. We examined how implicit and explicit temporal information established temporal expectations that influenced choice response times and response conflict (measured as flanker effects). We implicitly manipulated temporal structure by block-wise varying the likely timing of a target. In the short-interval block, a target was presented frequently (80 % of trials) after a short (400 ms) cue-to-target interval and infrequently (20 % of trials) after a long (1200 ms) interval; the probability assignment was reversed in the long-interval block. Building on this baseline condition (Experiment 1), we augmented the temporal information by filling the cue-to-target intervals with tones (Experiment 2), explicitly informed participants of the prevalent time interval (Experiment 3) and provided trial-by-trial reminders of the prevalent time interval (Experiment 4). The temporal probability manipulation alone (of which participants were unaware) influenced choice response times but only when the temporal information was augmented with tones, whereas providing the explicit knowledge of the temporal manipulation, with or without trial-by-trial reminders, robustly influenced choice response times. Response conflict was unaffected by these conditions. These results suggest that temporal expectation can be established by the implicit learning of a temporal structure given that sufficiently strong temporal information is presented as well as by the explicit knowledge of the temporal structure. This established temporal expectation influences choice response times without necessarily affecting the strength of response conflict.     

Flexible route selection by pigeons (Columba livia) on a computerized multi-goal navigation task with and without an "obstacle"

The ability to select efficient routes while reaching several locations, in situations addressed as the "traveling salesperson problem (TSP)", seems to play an important role in the lives of nonhuman species as well as humans. One of our previous studies with pigeons (Columba livia) used different variations of computerized navigation tasks to move a target to one or more goals, and showed that the birds consistently exhibited tendencies to visit the nearest goal first (Miyata & Fujita, 2010). Is this inflexible tendency consistent across all situations, or is it abandoned if it leads to a nonefficient strategy? The present study compared pigeons' route selection strategies in two-goal navigation tasks with and without having an L-shaped line as an obstacle barrier between the starting location of the target and the nearer goal. The pigeons frequently started by visiting the nearer goal in trials with no obstacles, whereas in trials having obstacles the birds often visited the farther goal first. For the detour trials with obstacles, the birds started from visiting the farther goal significantly more often than chance, even though disparity between the two traveling sequences was relatively small. The data demonstrated a case in which a tendency to visit the nearest goal was flexibly abandoned when the route required a detour behavior. Detailed analyses of the movement paths further suggest that the pigeons made decisions to choose a farther goal during the initial few steps, although a past history of reinforcement to avoid the barrier might have guided the birds' behavior.     

Awareness becomes necessary between adaptive pattern coding of open and closed curvatures

Visual pattern processing becomes increasingly complex along the ventral pathway, from the low-level coding of local orientation in the primary visual cortex to the high-level coding of face identity in temporal visual areas. Previous research using pattern aftereffects as a psychophysical tool to measure activation of adaptive feature coding has suggested that awareness is relatively unimportant for the coding of orientation, but awareness is crucial for the coding of face identity. We investigated where along the ventral visual pathway awareness becomes crucial for pattern coding. Monoptic masking, which interferes with neural spiking activity in low-level processing while preserving awareness of the adaptor, eliminated open-curvature aftereffects but preserved closed-curvature aftereffects. In contrast, dichoptic masking, which spares spiking activity in low-level processing while wiping out awareness, preserved open-curvature aftereffects but eliminated closed-curvature aftereffects. This double dissociation suggests that adaptive coding of open and closed curvatures straddles the divide between weakly and strongly awareness-dependent pattern coding.