Tactics to obtain a hidden food item in chimpanzee pairs (Pan troglodytes)

Five dyads of chimpanzees were tested in a competitive situation, as a pilot study to examine chimpanzees' understanding of conspecifics' knowledge. A human experimenter baited one of five containers in an outdoor enclosure. Chimpanzee A (witness) could see where the food was hidden, while chimpanzee B (witness-of-witness) could not see the baited place but could observe the chimpanzee A watching the food being hidden. Then the two were released into the enclosure. This procedure was repeated for a certain number of days along with a control condition in which neither could see the baited location. The witness-of-witness developed tactics to forestall the witness in two pairs. The witness misled the witness-of-witness by taking a route to an empty container in several cases. These episodes might represent examples of deception. Tactics and counter-tactics thus developed through the interaction between the witness and the witness-of-witness, illustrating the high social intelligence of chimpanzees. An examination of the changes in tactics suggests a possibility that the witness-of-witness understands the witness's knowledge of the location of hidden food. Accepted after revision: 22 May 2001 Electronic Publication     

Temporal and spatial parameters of stepping in place in children and adults

Characteristics of synchronized and self-paced stepping in place were examined by analyzing a temporal parameter (step frequency) and a spatial parameter (step height). Participants were 20 adults (10 women, 10 men; M age = 22.5 yr., range = 21-23) and 10 children (5 girls, 5 boys; M age=6.1 yr., range = 5-6). Results indicated that: (1) the step frequencies, which were equivalent for both groups, were well coincident with stimulus frequencies; (2) when step frequencies were imposed, the step height decreased with increasing step frequency, except for the lowest frequency condition in children; (3) movement consistency was the highest at 2 Hz and deteriorated if the step frequency was higher or lower; and (4) the self-paced stepping in place was optimal in terms of movement consistency. These results showed that stepping in place is a rhythmic movement at a given range of frequency which is coordinated so as to keep the product of step frequency and step height constant.     

How cattle discriminate between green and dead forages accessible by head and neck movements by means of senses: reliance on vision varies with the distance to the forages

Animal Cognition - The ability of ungulates to discriminate among vegetation patches depends largely on the senses of vision, olfaction, tactility, and gustation. However, little is known about how...     

Visual Dominance in Amending the Directional Parameter of Feedforward Control

The authors examined visual dominance between trials in which the movement program was amended (i.e., off-line processing). Weighting between visual and proprioceptive feedback was examined in a trial-by-trial analysis of the directional parameter of feedforward control. Eight participants moved a cursor to a target displayed on a computer screen by manipulating a hand-held stylus on a digitizing tablet. In the first 30 trials, the cursor followed the stylus movement (practice condition). In the next 30 trials, the directional error of the stylus movement was presented in the opposite direction (reversal condition). Subjects knew the presence and the nature of the reversal. In the last 10 trials, the reversal was withdrawn (transfer condition). Directional error of feedforward control was relatively small in the practice condition, and it increased gradually in 1 of 2 directions as trials proceeded in the reversal condition. Positive aftereffect was observed in the transfer condition. A constant increment of the directional error indicated that both visual and proprioceptive feedback are registered, with higher weight on vision, and that weighting between those inputs is determined automatically or is fixed without any strategic control.     

The Role of Recruit Division Commanders in Graduation From U.S. Navy Recruit Training

We investigated the importance of the role of drill instructors (RDCs) on training and retention of new sailors (N = 34,000). Based on social support and group cohesion literatures, we hypothesized that social support from RDCs would influence completion rates of entry-level Navy training and retention intention of new sailors. We found that perceptions of social support from RDCs had a significant positive relationship with eventual graduation from basic training; encouragement to remain in the Navy was particularly strongly related to graduation when the source of the encouragement was RDCs. Further, those who attrited from training were especially likely to perceive RDCs as encouraging them to leave the Navy. We discuss the implications of our findings in terms of theory, research and practice.     

The role of imagery-related properties in picture naming: A newly standardized set of 360 pictures for Japanese

Picture naming was investigated primarily to determine its dependence on certain imagery-related variables, with a secondary aim of developing a new set of Japanese norms for 360 pictures. Pictures refined from the original Nishimoto, Miyawaki, Ueda, Une, and Takahashi (Behavior Research Methods 37:398?C416, 2005) set were used. Naming behaviors were measured using four imagery-related measures (imageability, vividness, image agreement, and image variability) and four conventional measures (naming time, name agreement, familiarity, and age of acquisition), as well as a number of other measures (17 total). A simultaneous multiple regression analysis performed on naming times showed that the most reliable predictor was H, a measure of name diversity; two image-related measures (image agreement and vividness) and age of acquisition also contributed substantially to the prediction of naming times. The accuracy of picture naming (measured as name agreement) was predicted by vividness, age of acquisition, familiarity, and image agreement. This suggests that certain processes involving mental imagery play a role in picture naming. The full set of norms and pictures may be downloaded from http://www.psychonomic.org/archive/ or along with the article from http://www.springerlink.com.     

Are you listening? Exploring a developmental knowledge–action dissociation in a speech interpretation task

Young children sometimes act inappropriately despite appearing to know what to do. Dissociations of this kind raise important questions about the organization and development of knowledge and action systems. The present study investigated a knowledge–action dissociation in 6–year–olds performing a speech interpretation task and tested the hypothesis that knowledge–action dissociations stem from a general difficulty resolving conflicting cues. When knowledge and action measures were equated in terms of the amount of conflict that needed to be resolved for a correct response, children’s knowledge no longer appeared to outstrip their ability to act appropriately. Implications of the findings for competing views of knowledge representation and knowledge–action system organization are discussed.     

Attention level and negative priming in hierarchical patterns1

Abstract: This study explored object processing associated with attention level dependent on task, using a paradigm of negative priming. Participants were required to identify target characters that appeared at either the global or local level in hierarchically structured patterns. Two experiments were conducted to examine how the global and local characters were processed in the attended and unattended levels. In the results of Experiment 1, where stimuli were presented for 10 ms, negative priming was observed in a local‐directed task, but not in a global‐directed one. These results suggested that the inhibition of local characters in the unattended level did not occur during global attention. The results of Experiment 2 revealed that negative priming was observed in both global‐ and local‐directed tasks in the 500 ms presentation, showing that inhibition in the unattended level occurred. As a result, the exposure duration influences inhibition in the unattended, especially the local level. At short exposure duration, the local characters are not inhibited when one directs attention to the global characters, whereas these are inhibited at long exposure duration.     

Recognition and position information in working memory for visual textures

In three experiments, we examined connections between item-recognition memory and memory for item-position information. With sequences of compound gratings as study and probe items, subjects made either item-position judgments (Experiments 1 and 2), by identifying the serial position of the study item that matched the probe, or recognition judgments (Experiment 3), by judging whether the probe had or had not been presented in the study series. Integrating a summed-similarity account of recognition into a signal detection framework shows that the variance of summed similarities on lure trials (probe not present in the study series) exceeds the variance on target trials (probe present in the study series). This prediction is borne out by the empirical zROC functions, all of which had slopes that were greater than 1. Additionally, about 25% of correct recognitions were accompanied by incorrect item position identification. Misidentifications of item position arose from two sources--structural similarity and positional similarity-which combined in an approximately additive fashion.