Context-dependent olfactory learning monitored by activities of salivary neurons in cockroaches

Context-dependent discrimination learning, a sophisticated form of nonelemental associative learning, has been found in many animals, including insects. The major purpose of this research is to establish a method for monitoring this form of nonelemental learning in rigidly restrained insects for investigation of underlying neural mechanisms. We report context-dependent olfactory learning (occasion-setting problem solving) of salivation, which can be monitored as activity changes of salivary neurons in immobilized cockroaches, Periplaneta americana. A group of cockroaches was trained to associate peppermint odor (conditioned stimulus, CS) with sucrose solution reward (unconditioned stimulus, US) while vanilla odor was presented alone without pairing with the US under a flickering light condition (1.0 Hz) and also trained to associate vanilla odor with sucrose reward while peppermint odor was presented alone under a steady light condition. After training, the responses of salivary neurons to the rewarded peppermint odor were significantly greater than those to the unrewarded vanilla odor under steady illumination and those to the rewarded vanilla odor was significantly greater than those to the unrewarded peppermint odor in the presence of flickering light. Similar context-dependent responses were observed in another group of cockroaches trained with the opposite stimulus arrangement. This study demonstrates context-dependent olfactory learning of salivation for the first time in any vertebrate and invertebrate species, which can be monitored by activity changes of salivary neurons in restrained cockroaches.     

Perception of the end position of a limb loaded with a weight

We examined the effect of loading a weight on the perception of the end position of the limb. The participants haptically perceived where the end of their limb was located while they swung the limb or statically held it. The results showed that the loading of a weight influenced participants' perception only when they swung the limb; when the weight was attached to a participant's hand, the position was perceived to be farther from the body than when the weight was attached to the forearm or no weight was attached. We also found that the end position was generally underestimated when the participants swung their limb. On the other hand, when the participants statically held their limb, the perceived position was not affected by the loading of the weight and was rather precise. These results suggest that the perceptual system for limb end position is sensitive to changes in the surrounding haptic information caused by moving the limb.     

Sequential effects in face-attractiveness judgment

A number of studies have shown that current-trial responses are biased toward the response of the preceding trial in perceptual decisionmaking tasks (the sequential effect-Holland and Lockhead, 1968 Perception & Psychophysics 3 409-414). The sequential effect has been widely observed in evaluation of the physical properties of stimuli as well as more complex properties. However, it is unclear whether subjective decisions (e.g., attractiveness judgments) are also susceptible to the sequential effect. Here, we examined whether the sequential effect would occur in face-attractiveness judgments. Forty-eight pictures of male and female faces were presented successively. Participants rated the attractiveness of each face on a 7-point scale. The results showed that the attractiveness rating of a given face assimilated toward the rating of the preceding trial. In a separate experiment, we provided the average attractiveness rating by others for each trial as feedback. The feedback weakened the sequential effect. These findings suggest that attractiveness judgment is also biased toward the preceding judgment, and hence the sequential effect can be extended into the domain of subjective decisionmaking.     

Implicit transfer of spatial structure in visuomotor sequence learning

Implicit learning and transfer in sequence learning are essential in daily life. Here, we investigated the implicit transfer of visuomotor sequences following a spatial transformation. In the two experiments, participants used trial and error to learn a sequence consisting of several button presses, known as the m × n task (Hikosaka et al., 1995). After this learning session, participants learned another sequence in which the button configuration was spatially transformed in one of the following ways: mirrored, rotated, and random arrangement. Our results showed that even when participants were unaware of the transformation rules, accuracy of transfer session in the mirrored and rotated groups was higher than that in the random group (i.e., implicit transfer occurred). Both those who noticed the transformation rules and those who did not (i.e., explicit and implicit transfer instances, respectively) showed faster performance in the mirrored sequences than in the rotated sequences. Taken together, the present results suggest that people can use their implicit visuomotor knowledge to spatially transform sequences and that implicit transfers are modulated by a transformation cost, similar to that in explicit transfer.     

Western scrub-jays allocate longer observation time to more valuable information

When humans mentally reconstruct past events and imagine future scenarios, their subjective experience of mentally time travelling is accompanied by the awareness of doing so. Despite recent popularity of studying episodic memory in animals, such phenomenological consciousness has been extremely difficult to demonstrate without agreed behavioural markers of consciousness in non-linguistic subjects. We presented western scrub-jays (Aphelocoma californica) with a task requiring them to allocate observing time between two peepholes to see food being hidden in either of two compartments, one where observing the hiding location was necessary to later relocate the food, and another where food could easily be found without watching. Jays first separately experienced these consequences of possessing information in each compartment and subsequently, once given a choice, made more looks and spent more time looking into the compartment where information was necessary than into the compartment where it was unnecessary. Thus, the jays can collect information to solve a future problem. Moreover, they can differentiate sources of information according to their potential value and modify behaviour to efficiently collect important, usable information. This is the first evidence of metacognition in a species that passes the behavioural criteria for both retrospective and prospective mental time travel.     

Exogenous temporal cues enhance recognition memory in an object-based manner

Exogenous attention enhances the perception of attended items in both a space-based and an object-based manner. Exogenous attention also improves recognition memory for attended items in the space-based mode. However, it has not been examined whether object-based exogenous attention enhances recognition memory. To address this issue, we examined whether a sudden visual change in a task-irrelevant stimulus (an exogenous cue) would affect participants' recognition memory for items that were serially presented around a cued time. The results showed that recognition accuracy for an item was strongly enhanced when the visual cue occurred at the same location and time as the item (Experiments 1 and 2). The memory enhancement effect occurred when the exogenous visual cue and an item belonged to the same object (Experiments 3 and 4) and even when the cue was counterpredictive of the timing of an item to be asked about (Experiment 5). The present study suggests that an exogenous temporal cue automatically enhances the recognition accuracy for an item that is presented at close temporal proximity to the cue and that recognition memory enhancement occurs in an object-based manner.     

American-Japanese cultural differences in judgements of emotional expressions of different intensities

Although research has generated a wealth of information on cultural influences on emotion judgements, the information we have to date is limited in several ways. This study extends this literature in two ways, first by obtaining judgements from people in two cultures of expressions portrayed at different intensity levels, and second by incorporating individual level measures of culture to examine their contribution to observed differences. When judging emotion categories in low intensity expressions, American and Japanese judges see the emotion intended at above-chance rates, albeit lower than when judging high intensity faces. Also, American and Japanese intensity ratings of external displays and internal experiences differ dramatically for low intensity expressions compared to high intensity faces. Finally, the two cultural dimensions measured in this study—individualism versus collectivism (IC) and status differentiation (SD)—accounted for almost all of the variance in the observed differences. These findings are discussed in terms of their underlying possible mechanisms, and future research possibilities.     

Atomistic study of structural fluctuations during radiation-induced amorphization in the ordered intermetallic compound NiTi

We have carried out an atomistic study of electron-induced amorphization of an ordered intermetallic compound NiTi by means of in-situ high-resolution high-voltage electron microscopy observations and molecular dynamics simulations. Both theoretical and experimental results show that metastable nanometre-size atomic clusters form and disappear during irradiation, so that a spatiotemporal fluctuation under amorphization is induced. Mean-lifetime measurements of these clusters demonstrate that high-energy particle irradiation provides a useful tool to study dynamic fluctuations of the local atomic structure in the non-equilibrium open systems.     

Motor Learning as a Function of KR Schedule and Characteristics of Task-Intrinsic Feedback

Forty participants (age range = 18–35 years) practiced 1 of 2 versions of an aiming task (with or without spring resistance). Knowledge of results (KR) was provided to them either immediately or after a delay of 2 trials. Immediate KR led to significantly more accurate performance during the 80 trials in acquisition but significantly less accurate performance on a 40-trial retention test given 24 hr after practice. In addition, the spring version of the task was performed significantly less accurately than the no-spring version on the 24-hr retention test. Most important, a significant interaction on the 24-hr retention test revealed that performance of the no-spring version of the task, when KR had been given after a 2-trial delay, was significantly more accurate than performance of the other 3 combinations of task version and KR schedule. The results suggest that KR dependency in motor skill learning is related to familiarity with task-intrinsic feedback in addition to the schedule on which KR is presented.     

Metascientific foundations for pluralism in psychology

In this paper, I explore the metascientific basis for pluralism in psychology. In the first half, I outline the two levels of the metaparadigm: the epistemological and the methodological. The epistemological level includes the dichotomy between an internal, first-person point of view and an external, third-person one. The methodological level includes the dichotomy between explanation and understanding. The continuing debate regarding methodology, explanation versus understanding, has distinguished the human sciences from the natural sciences. Similarly, the continuing debate regarding the epistemological point of view has distinguished psychology from other sciences. I illustrate these points by placing various trends in psychology into the two-dimensional space formed by the two coordinate axes depicting the methodological and the epistemological dimensions. Each quadrant represents one definition of the object of psychology: quadrant 1 (internal, first-person - explanation) represents “consciousness;” quadrant 2 (internal, first-person - understanding) represents “experiences;” quadrant 3 (external, third-person - understanding) represents “meaningful acts and expressions;” and quadrant 4 (external, third-person - explanation) represents “behaviors and higher processes of the brain.” All of the trends within the history of psychology can be placed within this two-dimensional space. In the second half of the paper, I introduce the third level of the metaparadigm: the metapsychological level. This level includes the three different, and incompatible conceptions of humans: the first-person, the second-person, and the third-person conceptions. A third-person conception of humans is most compatible with trends placed in quadrant 4. A second-person conceptualization is most congruent with quadrant 3, and so on. Thus, the unification of psychologies emerges as not only difficult but actually unreasonable, because the plurality of psychological paradigms originates from the epistemological, methodological, and metapsychological levels of the metaparadigm.