Directional uncertainty in visually guided pointing

Studies of the relationship between stimulus-response uncertainty and reaction times indicate three qualitatively different functions: Hick's law, simple-choice step function, or flat curve (no effect at all). The extent of stimulus-response S-R) compatibility appears to interact with the effects of uncertainty on response times. One possible hypothesis regarding these various S-R uncertainty functions is that uncertainty will have an effect whenever the stimuli and their associated responses are not within the same egocentric spatial coordinates. We tested this hypothesis in 5 undergraduate participants (2 men, M age 18.7 yr., range 18-20) by investigating the time-course of pointing to peripherally located visual targets under four different levels of uncertainty (1, 2, 4, or 8 possible locations). Surprisingly, the resulting response function does not match any of those previously reported. Visually guided pointing produced a quadratic reaction time function as S-R uncertainty increases in log2 steps from 1 to 8.     

Comparing Chinese and Western Visitors’ Responses to Interpretive Signs at Chengdu Research Base of Giant Panda Breeding,China

ABSTRACT

Visitor experiences and interpretation at wildlife tourism sites are often designed to encourage visitors to adopt conservation actions. Typically, conservation messages are delivered via one-size-fits-all interpretive signage, with little consideration given to whether the same information attracts and engages different cultural groups. This study explores Chinese and international visitors’ perceptions of signage at the Chengdu Research Base of Giant Panda Breeding in China. Four sign prototypes were designed and a combination of visitor observations, interviews, and exit surveys were used to test their attracting and holding power. Comparisons of Chinese and Western visitors revealed no significant difference in the proportion who stopped to read signs. Preferences for signage elements were also similar across the two cultural groups; however, there were differences in terms of what visitors thought should be included in wildlife interpretation. Implications for the design and delivery of interpretation in Chinese wildlife tourism settings are discussed.     

Acquisition of a non-vocal ‘language’ by aphasic children

Alphasic children with serious language deficits were taught to communicate via a system of visual symbols originally devised by David Premack (1969) for use with chimpanzees. The subjects, lacking normal language, readily learned to express several language functions in this way (word, sentence, class-concept, question, negation). The linguistic status of ‘Premackese’ is questioned, and it is suggested that it is better viewed as a communication system. It may, therefore, be that the aphasic children lack some specifically linguistic ability.     

Effects of time and event uncertainty upon sequential information processing

Two experiments were conducted to investigate the psychological refractory period (PRP), a delay induced into the second of two reaction times (RT) when the interstimulus interval (ISI) is short. In Experiment1, time and event uncertainty were factorially varied by providing or not providing S with foreknowledge of the ISI and the order in which the two events would occur, respectively. ISIs of0, 50, 100, 200, and400 msec were used. Time and event uncertainty produced independent degradation of both RTs. Also, the second RT (RT ₂ ) was delayed at50 msec ISI when both time and event certainty were present. Experiment 2 attempted to replicate this latter finding using ISIs of0, 25, 50, 75, and100 msec. Delays in RT ₂ were found for the middle three values of ISI. These results were interpreted as supporting a modified single channel theory of the PRP.     

Tolerance to and residual effects of cocaine in squirrel monkeys depend on reinforcement-schedule parameter.

Lever pressing by 4 squirrel monkeys was maintained under a three-component multiple fixed-ratio schedule of food presentation; components differed with respect to ratio size. For each monkey, acute administration of cocaine (0.03 to 1.3 mg/kg, i.m.) produced dose-dependent decreases in overall response rate in each component. During repeated daily administration of 1.0 mg/kg of cocaine, tolerance developed to the rate-decreasing effects under each of the ratio contingencies, but developed to a greater extent and was evident in earlier parts of sessions for performance under the smaller ratios. Response rates of 2 monkeys increased above nondrug control levels despite the putative reinforcer not being consumed during the session. When saline or a smaller dose of cocaine was substituted for 1.0 mg/kg, response rates often were suppressed below nondrug control-level responding. This suppressive effect was observed in each monkey and was more likely to be observed and/or to be of greater magnitude in large-ratio components for 3 of the 4 monkeys. When saline was administered chronically at the end of the chronic-drug phase, response rates remained suppressed in the large-ratio component for 2 of the monkeys. There was, therefore, a schedule-dependent dissociation between behavioral tolerance and the residual effects: Tolerance was greater when small ratios were arranged, whereas the residual effects were more pronounced when larger ratios were arranged.