An animal model of the hyperactive-child syndrome suitable for the study of the effects of food additives

This report describes the use of an animal model for testing the relationship between the effects of ingesting food additives and hyperactivity. Telomian × beagle hybrid dogs were chosen as subjects because this breed has been observed to exhibit behavior seen as analogous to the hyperactivity of children. Two studies were conducted by adding or deleting butylated hydroxyanisole and Food, Drug, and Cosmetic red dye number 40 to the diet of each dog. A test of sitting was performed to measure the level of activity. While a relationship was not observed between the ingestion of the additive and the level of activity, several issues pertaining to the use of the animal model became apparent. These issues and the use of animals for future research in this area are discussed.     

Intracranial cannulation of small animals

Special difficulties are encountered when attempting to provide intracranial cannulation of small animals that have floating or fragile skull bones. The technique described was developed for mice but seems applicable to other species. The cannula system is inexpensive and easy to use. A wound clip anchor seems superior to either skull screws or bonded acrylic, producing less damage to the brain and no necrosis of bone or tissue on the wound margin. Patency data up to 25 days is presented, and the system is as efficacious as other techniques.     

A method for the analysis of complex avian song repertoires

A new method for the analysis of complex avian song repertoires is introduced. The method consists of sending a tape-recorded bird-song signal through five narrow band-pass filters and then to a five-channel high-speed pen recorder. A coding method that allows a researcher to convert the output from the pen recorder to numbers for later analysis by computer is described.     

The visual accommodation response during concurrent mental activity

Concurrent mental activity seems to be a significant, nonvisual factor affecting the human accommodation response. Two experiments were conducted to determine the direction and magnitude of this accommodation response. Experiment 1 employed a concurrent, written backwards counting task. Experiment 2 employed a concurrent, mental imagery task of “thinking near” and “thinking far.” In both experiments, the concurrent secondary task effected a cumulative accommodative shift toward the visual far point of from .25 to .75 diopter away from a near (3.0 diopter) target. This accommodative shift was observed only in the presence of a stimulus field and not in open-loop (analogous to empty-field) conditions. In addition, a long-term instability in the open-loop method of obtaining the dark focus was observed. Similarities between this accommodative shift and the pupillary response are noted. The accommodation response is discussed in relationship to both an attention-sharing and an involuntary autonomic response model.     

The contribution of visual persistence to the perceived duration of brief targets

Two experiments were conducted to examine the role of sensory persistence on tasks of perceived duration employing very brief visual stimuli. Using a standard temporal judgment task, the first experiment replicated both the “size effect” and “empty-filled” illusion reported by previous investigators. However, entirely comparable results were also found with a probematching task, which theoretically assesses the degree of persistence exhibited by a stimulus. The second experiment examined the effect of target luminance on perceived duration. Consistent with a sensory persistence interpretation, judgments of duration increased with increasing luminance. The results from the two experiments were discussed in terms of varying degrees of retinal persistence produced by different stimuli. This view was contrasted with currently dominant interpretations that postulate changes in perceived duration to reflect different information-processing requirements across stimulus conditions.     

The effects of spatial frequency and target type on perceived duration

Two experiments are reported that attempt to demonstrate a critical role played by sensory persistence on a standard perceived-duration task employing brief visual stimuli. Experiment 1 examined the effect on perceived duration of varying the spatial frequency of a target. For both 40- and 70-msec flashes, increased spatial frequency resulted in reduced estimates of perceived duration. These results were contrasted with predictions derived from cognitive processing models of duration perception. In Experiment 2, three typical types of target employed in current research (an outlined circle, a “noise”-filled circle, and a completely filled circle) were shown to differ significantly in their perceived duration and in their sensitivity to increases in physical duration. The results were discussed in terms of variable degrees of retinal persistence produced by the three types of targets. The possible implications for specific discrepancies in the literature and across-study comparisons in general were enumerated.     

Monaural localization: An analysis of practice effects

Four listeners (experimental group) received one trial a session for 60 sessions on a monaural localization task in which six loudspeakers, positioned 15 deg apart, were placed on the side of the functioning ear. Four additional listeners (control group) received 60 massed trials first and then one trial a session for 60 sessions. The stimulus consisted of a single train of five high-frequency pulses. An ANOVA conducted on the 60 trials distributed over sessions showed that the experimental group’s performance was significantly inferior to that of the control group. Members of the former continued to displace sounds toward the open ear throughout the entire test. Those of the control group exhibited this tendency, but to a much lesser extent. The experience of locating 60 massed trials clearly had a robust effect on subsequent performance. We contend that, by virtue of presenting only one trial a session, the magnitude of the massed-trial effect was little attenuated by our tests to measure it. We interpret our substantive finding to mean that during the 60 massed trials, the control group formed a perceptual representation of the auditory space which served it well when placed on the one-trial-a-session regimen. Those in the experimental group were unable to develop an adequate representation of the auditory space, presumably because their monaural localization experience was restricted to only one trial a session.     

Dynamic visual noise and the stereophenomenon: Interocular time delays,depth, and coherent velocities

Attention, Perception, & Psychophysics - This study concerns the stereophenomenon obtained with binocular viewing of dynamic visual noise with a neutral density filter over one eye. Such a...     

Target-size influences on reaction time with movement time controlled

The variable that affect motor programming time may be studied by changing the nature of the response and measuring the subsequent changes in reaction time (RT). One notion of motor programming suggests that aiming responses with reduced target size and/or increased target amplitude require more "complex" motor programs that require longer RTs. In a series of five experiments which movement time (MT) was experimentally varied target size neither influences RT when the movement amplitude was 2 or 30 cm nor when the target sizes differed by as much as a factor of 16:1. Increasing the movement amplitude from 15 to 30 cm also had no influence on RT. Movement time, however, did affect RT, with 200-msec movements having longer RTs than 120-msec movements. Target size and movement amplitude did not appear to be factors that influence programming time or program complexity.