Spontaneously occurring mother-infant swapping and the relationships of infants with their biological and foster mothers in a captive group of lowland gorillas (Gorilla gorilla gorilla)

The present study describes spontaneously occurring infant-mother swapping and the relationships of infants with their biological and foster mothers after swapping in a captive social group of lowland gorillas (Gorilla gorilla gorilla). After infant-swapping took place between a primiparous mother with a neonate and a multiparous mother with a 10-month-old infant, the mothers provided appropriate maternal care, including nursing, to their adopted infants, but the older infant still sought refuge with its biological mother more frequently than with its foster mother. Almost 2 years later, the younger infant who was weaned by its foster mother began nursing from its biological mother; the latter subsequently weaned her adopted infant. Thereafter, the older infant who was weaned exhibited an abnormal hair-plucking behavior. These results indicate that it was psychologically stressful for the gorilla infant to quickly transfer its attachment figure from the mother to another adult female when the mother continued to remain in the group.     

The effects of differential training procedures on linked perceptual class formation

When the stimuli in one perceptual class (A') become related to the stimuli in another perceptual class (B'), the two are functioning as a single linked perceptual class. A common linked perceptual class would be the sounds of a person's voice (class A') and the pictures of that person (class B'). Such classes are ubiquitous in real world settings. We describe the effects of a variety of training procedures on the formation of these classes. The results could account for the development of naturally occurring linked perceptual classes. Two perceptual classes (A' and B') were formed in Experiment 1. The endpoints of the A' class were called anchor (Aa) and boundary (Ab) stimuli. Likewise, the anchor and boundary stimuli in the B' class were represented as Ba and Bb. In Experiment 2, the A' and B' classes were linked by the establishment of one of four cross-class conditional discriminations: Aa-->Ba, Aa-->Bb, Ab-->Ba, or Ab-->Bb. Results were greatest after Aa-->Bb training, intermediate after Aa-->Ba and Ab-->Ba training, and lowest after Ab-->Bb training. Class formation was influenced by the interaction of the anchor/boundary values and the sample/comparison functions of the stimuli used in training. Experiment 3 determined whether class formation was influenced by different sets of two cross-class conditional discriminations: Aa-->Ba and Ab-->Bb, or Aa-->Bb and Ab-->Ba. Both conditions produced equivalent results. Similarities were attributable to the use of anchor stimuli as samples and boundary stimuli as comparisons in each training condition. Finally, the results afterjoint Aa-->Ba and Ab-->Bb training were much greater than those produced by summing the results of Aa-->Ba training alone and Ab-->Bb training alone. This same synergy was not observed after joint Aa-->Bb and Ab-->Ba training or either alone.     

Selfish strategies develop in social problem situations in chimpanzee (Pan troglodytes) mother–infant pairs

Humans employ various strategies, including selfish and altruistic strategies, depending on the situation. In order to examine whether non-human animals show such flexibility or not, we analyzed chimpanzees’ selfish and cooperative behavior in two types of social problem situations. In this study, we tested chimpanzee mother–infant pairs in two adjacent booths, each equipped with a vending machine. When a token was inserted into a vending machine, the vending machine delivered food rewards to the adjacent booth. In experiment 1, a partition between the two booths was open. In experiment 2, the partition was closed and a mother and her infant were placed in separate booths, so that reciprocal cooperation was essential for them to receive rewards. The participants did not cooperate reciprocally in either experiment. In experiment 1, the chimpanzees developed selfish tactics to get rewards and changed their tactics flexibly according to the partner’s behaviors. In experiment 2, in which they could not receive rewards without cooperation, they stopped altogether inserting tokens. In both cases, the infants stopped cooperating first. These findings support the idea that chimpanzees are primarily competitive rather than cooperative. Chimpanzees’ high social intelligence might be demonstrated in the flexibility of their selfish tactics, but not in the form of reciprocal cooperation at least when food is involved. We suggest that the failure to establish reciprocal cooperation was due to the social relationship between the mother and her infant, which was characterized by infant’s privilege and mother’s tolerance.     

Token transfer between mother and offspring chimpanzees (Pan troglodytes): mother–offspring interaction in a competitive situation

Chimpanzees can flexibly use tokens in cognitive tasks, but it is still unknown if they can share and/or compete over tokens as they do for food. This study aimed to evaluate the interactions spontaneously occurring between mother and offspring chimpanzees when tokens exchangeable for food were provided. Forty tokens were scattered on the floor in an experimental playroom. Three mother and offspring chimpanzee pairs were tested. Each token was exchangeable for a piece of food in a vending machine installed on the wall of the playroom. In the beginning of the study, both mother and offspring took tokens and exchanged them for pieces of food independently. Later, two offspring started to take more tokens than their mothers. At that time, the offspring whimpered or cried more often than during earlier sessions. This behavior compelled the mothers to abstain from taking tokens. The mothers sometimes shared their tokens with their offspring, or were tolerant of their offspring taking their tokens from their hand. For one pair, the offspring sometimes shared tokens with her mother when her mother begged for the tokens. These results suggest that chimpanzees’ cognitive abilities enable them not only to use tokens, but also to compete for tokens, as they do for food. The results also suggest that token sharing between mother and offspring may be bidirectional and that transfer of tokens mainly occurs as a result of begging, although on some occasion offspring were able to obtain a token directly from his/her mother through tolerated scrounging.     

Gravity bias in young and adult chimpanzees (Pan troglodytes): tests with a modified opaque-tubes task

Young human children at around 2 years of age fail to predict the correct location of an object when it is dropped from the top of an S-shape opaque tube. They search in the location just below the releasing point (Hood, 1995). This type of error, called a 'gravity bias', has recently been reported in dogs and monkeys. In the present study, we investigated whether young and adult chimpanzees also show such a gravity bias in a modified version of the original opaque-tube task. The original task by Hood and colleagues required the subject to search in a location after the object had fallen, while in the task reported here, subjects were required to predict the location before the object was dropped. Thus the present procedure does not involve explicit invisible displacement operations, one of the important components of the original procedure. In Experiment 1 both young (1.5-2.5-year-old) and adult chimpanzees predicted the location of falling food items below the releasing point even when crossed tubes were used. These gravity errors remained after the extensive experience of using the tubes themselves. Experiment 2 further tested adult and 4-year-old chimpanzees under the set-up in which the straight and crossed tubes were simultaneously presented. The results were the same as those in the previous test, suggesting that developmental changes and learning effect do not affect the gravity bias in chimpanzees.     

Beyond Dichotomy—Towards Creative Synthesis

There are two ways for overcoming limitations of methods used in psychology, as Toomela (Integr. Physiol. Behav. Sci. doi:, 2007) points out. These are inventing new methods of research, and looking back into the history of methodological thought for new ideas. Though he limited the former as if it is a quantitative area and he declared to take the latter path, his paper actually advocates the need to create new methodology for understanding the human psyche through historical approach. We discuss problems of sampling and generalization in that context, and suggest a new way to creative synthesis through elaboration of qualitative methodologies. To us this direction constitutes an updated version of the German–Austrian methodology exactly as Toomela suggests.

High risk factors of hostage barricade incidents in a Japanese sample

Hostage taking incidents in which the police besiege a particular location are known as hostage barricade incidents. The first aim of the present article was to examine the process of risk assessment in hostage incidents, using a group of police officers as the sample. The second aim was to identify the risk factors involved in hostage incidents and examine the degree of concordance between the risk as assessed by the police officers and the figures obtained from the analysis of actual hostage barricade incidents. For the purpose of this study, a survey was carried out across Japan, and 45 police officers responsible for hostage negotiation responded to the questionnaires. Additionally, a sample of 116 actual hostage barricade incidents that occurred in Japan from 1970 to 2002 was utilised to examine the high risk factors involved in such cases. As per the results, a majority of the police officers (73.3%), in response to an open‐ended question, indicated that the highly excited state of the hostage takers was dangerous for the hostages. Moreover, it was demonstrated in all 116 incidents that several factors such as ‘a long siege’ tended to increase the risk of deaths, though this was very rare (n = 4). On the other hand, the proportion of injuries to the hostages was high in expressive situations such as domestic situations or suicide attempt scenarios. On the whole, the results obtained from the analyses of actual incidents were consistent with those obtained from the police officers' risk assessment in many respects. However, the correlation between the degree of risk as assessed by the police officers and the actual rate of deaths/injuries to the hostages was very low. Copyright © 2004 John Wiley & Sons, Ltd.     

The Story-Presenting Method: a Method for Constructing Multiple Viewpoints to Understand Different Cultures

This study will show the results of four dialogical cultural exchange classes, which were held between Japanese and Chinese high school students, and examine the shifts in students’ viewpoints and changes in cultural understandings that occurred during those classes. In the first cultural exchange class, students of both countries read a story which described an older student who carelessly wore a T-shirt inside out, and younger students passed by without greeting him. Students of both countries were then asked to write their comments about it. From the second to the fourth class, students discussed the story with each other through exchanging their comments. By presenting another story, which introduced the viewpoint of a third person, and asking them questions that allowed them to reflect on their lives, students also experienced four different viewpoints during these cultural exchange classes. At the beginning of the cultural exchange, students of both countries tended to focus on the similarities in each other’s comments, which led to the closing down of the discussion. However, through discussions and experiencing the four different viewpoints, they found there are some essential differences between them around ‘ways of greeting’ and ‘hierarchical relationships between older and younger students’, which motivated them to understand their counterparts’ culture. Moreover, in the last comments of these cultural exchange classes, it was found that they acquired the viewpoints of cultural others. Given the results of these classes, it is shown that it is effective to present various stories to stimulate cultural understanding.     

Hippocampal activation of immediate early genes Zenk and c-Fos in zebra finches (Taeniopygia guttata) during learning and recall of a spatial memory task

Zebra finches (Taeniopygia guttata) are able to learn the position of food by orienting on spatial cues in a ‘dry water maze’. In the course of spatial learning, the hippocampus shows high expression of the immediate early genes (IEGs) Zenk and c-Fos, indicating high activation of this area during learning. In contrast, the IEG activity is nearly absent if the birds do not have to rely on spatial cues. In the present experiment it was investigated whether hippocampal activation can also be observed if the learned spatial task is recalled. For this purpose, the hippocampal Zenk and c-Fos activation of birds in an early learning stage was compared with that of others having well reached their maximal performance. The results show that the avian hippocampus is also active during recall of a learned spatial task, but the activation is significantly lower than in animals learning actually. As in previous experiments, hippocampal IEG expression showed strong variation not only in the position of the active patches of neurons, but also in size and cell density. The observed difference contributes to the view that immediate early genes may not be indicators of activation alone, but may be due to a combination of activation and plastic changes.