Extinction revisited: similarities between extinction and reductions in US intensity in classical conditioning of the rabbit's nictitating membrane response

The mechanisms of extinction were examined by reducing the intensity of the unconditioned stimulus (US) after acquisition training to determine whether such reductions lie on a continuum with CS-alone extinction. The experiments revealed that reductions in US intensity yielded extinction-like effects. Specifically, there were proportional reductions in the daily mean level of responding across sessions. There were also persistent within-session declines and between-session increases of responding analogous to spontaneous recovery. Surprisingly, even when US intensity was held constant, within-session declines and between-session increases were apparent. The results are discussed with respect to possible contributions from unlearning, new learning, generalization decrement, and nonassociative loss, especially CS-specific attentional changes and CR-specific reactive inhibition.     

Does priming specific syllables during tip-of-the-tongue states facilitate word retrieval in older adults?

This experiment investigated whether phonological priming of syllables helps resolve tip-of-the-tongue (TOT) states in young and older adults. Young, young-old, and old-old adults read general knowledge questions and responded "know," "TOT," or "don't know" accordingly. Participants then read a list of 10 words that included 3 phonological primes corresponding solely to the first, middle, or last syllable of the target word. Young and young-old adults resolved more TOTs after first-syllable primes, but old-old adults showed no increase in TOT resolution following any primes. These results indicate that presentation of the first syllable of a missing word strengthens the weakened phonological connections that cause TOTs and increases word retrieval, but not for old-old adults who experience greater deficits in the transmission of priming across these connections.     

Odorant quality perception: a metric individual differences approach

Perceptual spaces, in which similar stimuli are located close to each other and dissimilar stimuli are located far apart, have aided in the understanding of the physiological and psychological bases for sensory quality coding. Differences in perception between individuals should be reflected by differences in the spatial relationships between stimuli. If the dimensionality of the perceptual space is small (e.g., color space), individual differences that reflect specific pathologies are readily apparent from visual inspection. On the other hand, if the dimensionality of the perceptual space is large (as is proposed for odor space), visual inspection alone may not reveal individual differences in quality perception. The present work presents an information-theory-based method for quantifying individual differences in quality perception from perceptual confusion matrices. The ability of this method to quantify individual differences in quality perception is shown in a hypothetical example of specific anosmia. Finally, the method is applied to the examination of intrasubject consistency of odorant quality perception.     

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On the effects of signaling reinforcer probability and magnitude in delayed matching to sample

Two experiments examined whether postsample signals of reinforcer probability or magnitude affected the accuracy of delayed matching to sample in pigeons. On each trial, red or green choice responses that matched red or green stimuli seen shortly before a variable retention interval were reinforced with wheat access. In Experiment 1, the reinforcer probability was either 0.2 or 1.0 for both red and green responses. Reinforcer probability was signaled by line or cross symbols that appeared after the sample had been presented. In Experiment 2, all correct responses were reinforced, and the signaled reinforcer durations were 1.0 s and 4.5 s. Matching was more accurate when larger or more probable reinforcers were signaled, independently of retention interval duration. Because signals were presented postsample, the effects were not the result of differential attention to the sample.     

Perceptions of Dating Violence Following a Sexualor Nonsexual Betrayal of Trust: Effects of Gender, Sexism, Acceptance of Rape Myths, and Vengeance Motivation

College womens (N = 220) and mens (N = 208) perceptions of violence following a betrayal by a romantic partner were studied in an independent groups design that varied gender of the participant, type of betrayal (sexual or nonsexual), and gender of the betrayed individual. Participants read one of four brief vignettes in which the betrayed person slapped his/her partner and made his/her lip bleed. Justification of this action was rated on 10 items. Factor analysis of these items indicated the presence of three factors for men and four for women. Both men and women indicated that hitting the partner, getting even, and being angry were more justifiable following a sexual betrayal. The hitting of a male partner by a betrayed woman was perceived as more justified than the hitting of a female partner by a betrayed man. In absolute terms, hitting and getting even by both women and men were generally viewed as unjustifiable, whereas being angry was viewed as justifiable. For both women and men, scores on the Vengeance Scale (Stuckless & Goranson, 1992) and Rape Myth Acceptance Scale (Lonsway & Fitzgerald, 1995) were related to getting even. For men, the Hostile Sexism Scale (Glick & Fiske, 2001) was related to getting even or being angry and breaking up. Results indicated that perceptions of reactions to betrayal are related to type of betrayal and to the dispositional characteristics of the perceiver.     

How do giant pandas (Ailuropoda melanoleuca) respond to varying properties of enrichments? A comparison of behavioral profiles among five enrichment items

This study investigated the responses of 14 giant pandas (Ailuropoda melanoleuca) to 5 enrichment items (3 manipulable objects, 2 feeding devices) that possess different properties affording varying behavioral opportunities. Enrichment items were quantitatively described by using 12 properties. Pandas displayed no preferences among the 5 enrichment treatments, all of which had similar positive effects on behavioral measures of well-being (behavioral diversity, stereotypy). However, each item promoted a distinct behavioral profile, readily mapped onto the enrichment's properties. These results suggest that it may be important to stimulate behavioral diversity but that specific behaviors or enrichment properties are not required. The unique behavioral topography seen with these enrichments also suggests that providing multiple enrichments with varying properties will maximize overall behavioral diversity.