Food anticipation and lever-directed activities in rats

Three experiments are described which elaborate some of the conditions under which rats will contact and manipulate a periodically presented retractable lever. Experiment 1 demonstrated that (i) initial manipulative oral and manual contact with the lever was facilitated if the rat had previous experience of food delivery in the experimental chamber; (ii) persistence in contacting the lever on successive presentations was a function of whether food continued to be presented in the experimental environment; and (iii) food satiation significantly reduced the tendency of the rat to contact the lever even though an expectancy of food had previously been established under conditions of food deprivation. Experiment 2 suggested that the tendency to approach and contact the lever was in part a function of the local moment-to-moment conditional probability of food delivery. Experiment 3 found that the probability of contacting the lever was higher during presentation of an auditory CS signaling a high rate of food delivery than during stimuli signaling no food at all. These results are interpreted as suggesting that the food-signaling aspects of an appetitive CS and that CS's ability to generate signal-directed behaviors are experimentall separable properties.     

Children's scales of length and loudness: A developmental application of cross-modal matching

The cross-modal matching techniques that have produced scales of sensory magnitude for a variety of perceptual continua in adults were used to construct similar scales in children. Subjects were adults and children 4, 6, 8, and 12 years old. Their task was, first, to match the loudness of a 1000-Hz tone to various visual lengths, and, second, to match the length of a white tape to various loudnesses of the tone. Almost all subjects were able to perform the matching tasks; the average precision of older subjects (12 and Adult) was somewhat greater, but in each of the younger age groups a majority of subjects performed with a precision that equaled that of older subjects. The exponent of the power function that relates length and loudness does not change with age. The scale factor does change, in a way that suggests either that a given sound intensity seems softer, or, more probable, that a given length seems longer, to younger children. The success of cross-modal matching with subjects as young as 4 years means that it is possible to investigate not only single perceptual scales but also intermodal organization in young children.     

Analysis of the development of children's spatial reference systems

Four, six, and ten-year-old children were required to copy an object's location and orientation within a two-dimensional spatial layout under two conditions: when both E's standard board and that of the S's were in the same orientation and when they were rotated 180 ° from each other. The failure of the 4-yr-olds to copy location and orientation under both conditions even when space was topographically coded indicates that at this age the child does not conceptualize space within two dimensions. Although the errors of the 4-yr-olds tended to be of a self-reference nature with respect to orientation and location on rotation trials the axes of the self-reference system were not coordinated. Six and 10-yr-old children performed significantly better on both conditions, with the exceptions that the 6-yr-olds continued to preserve some orientations within a self-reference system. When topographical codes were removed and S imagined rotation there were no significant age differences in total errors; however, older children organized entire subspaces within a self-reference system. The findings support Piaget and Inhelder's hypothesis that two-dimensional reference systems do not develop until the period of concrete operational thought, and they also indicate that even at age 10, the self-reference system continues to function when topographical codes are absent. Several cognitive mechanisms proposed to account for the development of spatial abilities are critically discussed.     

Children's size judgments when size and distance vary: Is there a developmental trend to overconstancy?

A review of the experimental literature on size constancy in children shows that studies permitting unrestricted viewing in natural settings provide only limited support for the hypothesis, proposed by Wohlwill, of a developmental trend from under- to overconstancy. A study is reported in which subjects aged 8 to 18 years made magnitude estimations of height for targets whose height and distance from them varied. For distances up to 15 m, and heights from 5 to 50 cm, size constancy prevailed at all ages: The same number was assigned to a given height at every distance. If a developmental trend exists, it requires either younger subjects or greater distances to be revealed.     

Cue exposure and response prevention with alcoholics: a controlled trial

Ten severely alcohol-dependent subjects were divided into two groups, one of which received only 6 sessions of in-vivo cue exposure and response prevention and the other of which received 6 sessions of imaginal cue exposure, followed by 6 sessions of in-vivo cue exposure and response prevention. The in-vivo cue exposure produced significant decrements on behavioural and subjective measures for both experimental groups on Desire to Drink and Difficulty to Resist Alcohol. Imaginal cue exposure produced trivial changes on these measures. The implications for both theory and practice are discussed.     

A demonstration of intransitivity in natural categories

Two experiment are reported which demonstrated intransitivity in category judgments, thus challenging a widely held assumption that the relation between categorized sets is one of class inclusion. Subjects consistently accepted the truth of certain category statements, in spite of being aware of the existence of counterexamples. Implications for semantic memory theory are discussed.     

The limits of perceived magnitude: Comparison among individuals and among perceptual continua

Two models of perceived magnitude that focus on the concept of dynamic range (DR) for sensory systems are summarized and compared. The first asserts that, whereas the size of DR varies physically from one perceptual continuum to another, all are subjectively equal. The other asserts that, for any given continuum, whereas the size of DR varies over individual observers, the subjective range does not.A test of the second model is reported for perceived effort for a range of loads on a bicycle ergometer. Both DR and judgmental (magnitude estimation) range estimates were obtained for 30 subjects. The former exhibited the expected variability over subjects, but there was no support for the predicted invariance of the latter. However, it is concluded, first, that the finding constitutes disconfirming evidence for the second model only if it is assumed that magnitude estimates are proportional to perceived magnitude, an issue which itself remains in dispute, and second, that the testability of the second model is doubtful unless a measure can be identified that is a stateable function of perceived magnitude.     

Effects of displacing aggression by annoyed and nonannoyed subjects

Low hostility-guilt subjects were either annoyed or not annoyed by an experimental confederate and given the opportunity to (a) displace aggression against a second confederate in a memory task, (b) go through a similar task but not aggress, or (c) sit quietly for a comparable period of time. All subjects were subsequently allowed to aggress against their annoyer in a “creativity” task. While displacement following annoyance did not reduce physiological arousal, it did reduce the amount of subsequent aggression against the annoyer. Conversely, the expression of aggression in subjects who were not annoyed resulted in an increase in physiological arousal, but not in subsequent aggression. No significant relationships were found between physiological arousal and subsequent aggression.     

Infant responses of ocular fixation to moving visual stimuli

Infants of 1, 2, and 3 months of age were presented with two checkerboard patterns, one stationary and the other moving in a horizontal oscillatory motion at one of eight rates. An observer who could see only the infant's head and eyes recorded, for each 30-sec trial, (a) the position of first fixation, (b) position of fixation at the end of each 5-sec interval, and (c) a final forced-choice judgment of the position of the moving stimulus. Results showed reliable differences in ocular behavior as a function of rate of stimulus motion for all three groups of infants.