Label training and auditory generalization

To investigate the Miller-Dollard hypothesis (Social learning and imitation, New Haven: Yale University Press, 1941) that verbal labels increase distinctiveness of cues, generalization gradients to pure tones were obtained before and after label training. One group was trained to label all seven tones in an array and another only the middle tone. Three additional groups controlled for nonverbal factors. Before training, gradients were characterized by progressive loss of stimulus control with exposure to the generalization test stimuli. The main effect of possession of labels was to retard this loss, but only in tests where S+ was a labeled stimulus. While the specificity of label effects was in line with the Miller-Dollard hypothesis, the finding that labels did not confer a clear advantage at the start of testing was not. It was suggested that the unlabeled stimuli may have been sufficiently distinct to mask label effects and that interference generated by the test stimuli reduced distinctiveness to levels needed for such effects to emerge.     

Gradients of auditory generalization for blind, retarded children

Severely retarded, blind children were conditioned to respond differentially to two intensities of a pure tone. Gradients of auditory generalization were obtained that were reliable and similar to those for normal adults, but often asymmetric and non-monotonic.     

Increasing CREB in the auditory thalamus enhances memory and generalization of auditory conditioned fear

Although the lateral nucleus of the amygdala (LA) is essential for conditioned auditory fear memory, an emerging theme is that plasticity in multiple brain regions contributes to fear memory formation. The LA receives direct projections from the auditory thalamus, specifically the medial division of the medial geniculate nucleus (MGm) and adjacent posterior intralaminar nucleus (PIN). While traditionally viewed as a simple relay structure, mounting evidence implicates the thalamus in diverse cognitive processes. We investigated the role of plasticity in the MGm/PIN in auditory fear memory. First we found that auditory fear conditioning (but not control manipulations) increased the levels of activated CREB in both the MGm and PIN. Next, using viral vectors, we showed that exogenously increasing CREB in this region specifically enhanced formation of an auditory conditioned fear memory without affecting expression of an auditory fear memory, formation of a contextual fear memory, or basic auditory processing. Interestingly, mice with increased CREB levels in the MGm/PIN also showed broad auditory fear generalization (in contrast to control mice, they exhibited fear responses to tones of other frequencies). Together, these results implicate CREB-mediated plasticity in the MGm/PIN in both the formation and generalization of conditioned auditory fear memory. Not only do these findings refine our knowledge of the circuitry underlying fear memory but they also provide novel insights into the neural substrates that govern the degree to which acquired fear of a tone generalizes to other tones.     

Operant generalization of auditory tempo in quail neonates

Operant generalization, a building block of cognition, has never been studied in neonates. We developed a preparation for newly hatched quail in order to investigate the form of the generalization gradient very early in development. For their first 4–5 days after hatching, northern bobwhite chicks pecked for brief heat presentations while hearing a high-pitched sound repeated at a constant rate (nondifferential training). Tempo generalization was then assessed in extinction. A significantly excitatory average gradient resulted despite minimal postnatal experience.     

Lack of bilateral generalization of adaptation to auditory rearrangement

Intermanual transfer of adaptation to rearranged ear-hand coordination, generated by exposure to auditory rearrangement entailing 30 deg of functional rotation of the interaural axis by electronic pseudophones, was explored using 16 Ss. The results show that, except for one exposure condition, changes in ear-hand coordination that compensate the distortion induced by the pseudophones fail to transfer intermanually. These findings are similar to observations on visual adaptation.     

Some effects of response-independent reinforcement on auditory generalization gradients.

Two groups of six rats received discrimination training with two auditory stimuli differing in intensity. During one stimulus, the schedule was variable interval; during the other, it was either variable time or extinction. Both the variable time and extinction schedules resulted in differential rates of responding in the presence of the two stimuli. Extinction resulted in an earlier and more stable difference. Stimulus generalization gradients obtained along the noise-intensity dimension revealed peak shift with both procedures. In addition, a secondary peak to stimuli in between the two training stimuli occurred with the variable-time schedule.     

The ontogeny of auditory frequency generalization in the chicken.

To determine if there is an ontogenetic change in stimulus coding, chickens between the day of hatching and 9-10 days old were tested using a habituation-generalization paradigm. Experiment 1 indicated that 1 day-old and 3--4-day-old chicks show similar habituation of an eye-opening response to auditory stimuli in the 800--1,200-Hz range. In Experiment 2 the eye-opening response to a 1,000-Hz stimulus was habituated and then immediately tested using stimuli which varied between 800 and 1,200 Hz. Each age-group (1 day, 3--4 days, and 9--10 days) showed a symmetrical stimulus generalization gradient around the 1,000-Hz stimulus and the 1-day-old chicks displayed a reliably flatter gradient than either of the older groups, which did not differ. In a third experiment, the position of the gradients relative to the baseline was shifted without altering the relative shapes. These results allow general arousal, general auditory responsiveness, overall error rate, and metric characteristics of the independent and dependent variables to be eliminated as possible sources of the age differences in gradient shape. The changes in stimulus generalization, therefore, support the view that during normal development there is a sharpening of perceptual coding processes.     

Reliability generalization: a viable key for establishing validity generalization

Even with radical restriction of range, reliability coefficients from 10 studies gave an average interstudy value of .74, suggesting constancy of reliability over diverse experiments. A value from a new test can help index reliability of tests not previously studied.     

Further generalization technology: Accounting for natural covariation in generalization assessment

In recent years, the assessment of generalization effects has become a major priority of applied behavior analysis. In this paper we propose a set of procedures to increase the accuracy of generalization assessments by accounting for the degree of natural covariation between treated and untreated behaviors. Scatterplot analyses were used (a) to assess the amount of baseline and postbaseline covariation between behaviors, (b) to determine if the observed generalization effect was due to a preexisting covariation between the behaviors, and (c) to assess if there is a significant change in the strength of the relationship between the behaviors as a function of the intervention. Six hypothetical sets of data are used to demonstrate how these procedures provide more accurate and detailed generalization assessment.     

Conceptual priming for realistic auditory scenes and for auditory words

Two experiments were conducted using both behavioral and Event-Related brain Potentials methods to examine conceptual priming effects for realistic auditory scenes and for auditory words. Prime and target sounds were presented in four stimulus combinations: Sound–Sound, Word–Sound, Sound–Word and Word–Word. Within each combination, targets were conceptually related to the prime, unrelated or ambiguous. In Experiment 1, participants were asked to judge whether the primes and targets fit together (explicit task) and in Experiment 2 they had to decide whether the target was typical or ambiguous (implicit task). In both experiments and in the four stimulus combinations, reaction times and/or error rates were longer/higher and the N400 component was larger to ambiguous targets than to conceptually related targets, thereby pointing to a common conceptual system for processing auditory scenes and linguistic stimuli in both explicit and implicit tasks. However, fine-grained analyses also revealed some differences between experiments and conditions in scalp topography and duration of the priming effects possibly reflecting differences in the integration of perceptual and cognitive attributes of linguistic and nonlinguistic sounds. These results have clear implications for the building-up of virtual environments that need to convey meaning without words.     

Feature selection for inductive generalization

Judging similarities among objects, events, and experiences is one of the most basic cognitive abilities, allowing us to make predictions and generalizations. The main assumption in similarity judgment is that people selectively attend to salient features of stimuli and judge their similarities on the basis of the common and distinct features of the stimuli. However, it is unclear how people select features from stimuli and how they weigh features. Here, we present a computational method that helps address these questions. Our procedure combines image-processing techniques with a machine-learning algorithm and assesses feature weights that can account for both similarity and categorization judgment data. Our analysis suggests that a small number of local features are particularly important to explain our behavioral data.     

Categorizing numeric information for generalization

Learning programs that generalize from real-world examples will have to deal with many different kinds of data. Continuous numeric data can cause problems for algorithms that search for examples with identical property values. These problems can be surmounted by categorizing the numeric data. However, this process has problems of its own. In this paper, we look at the need for categorizing numeric data and several methods for doing so. We concentrate on the use of generalization-based memory, a memory organization where actual examples are stored along with generalizations, which leads to a generalization-based categorization algorithm. We also consider how to use a number heuristic, looking for gaps. These methods have been implemented in the UNIMEM computer system. Examples are presented of these algorithms categorizing data about the states of the United States.     

A novel signal processing approach to auditory phantom perception

Psychonomic Bulletin & Review - The ear and brain interact in an orchestrated manner to create sensations of phantom tones that are audible to listeners despite lacking physical presence in...     

Concurrent generalization gradients for food-controlled and shock-controlied behavior

In the presence of a bright light, monkeys were trained to press a lever to avoid shock and to pull a chain for food reward. After gradients of generalization to other light intensities had been determined for each response, gradients were subsequently secured after training in a brightness discrimination and under several free-shock conditions. The following results were obtained: (1) Generalization gradients prior to discrimination training were much steeper for the food-controlled response than for the shock-controlled response. This finding was confirmed in another study in which rats served as subjects. (2) After discrimination training, both gradients became much steeper, but the avoidance gradient still showed more generalized responding than that of reward. (3) After a period of continuous testing with all the different test intensities, the two gradients became even steeper. In addition, differences between the two gradients virtually disappeared. (4) The intermittent delivery of free shocks during a previously non-shocked light intensity radically affected the shape of the avoidance gradient, just as the addition of an avoidance contingency did during the same, previously non-shocked, light intensity.