Effects Of Stimulus Novelty Research Articles

The time course of stimulus-specific perceptual learning.

Practice on perceptual tasks can lead to long-lasting, stimulus-specific improvements. Rapid stimulus-specific learning, assessed 24hours after practice, has been found with just 105 practice trials in a face identification task. However, a much longer time course for stimulus-specific learning has been found in other tasks. Here, we examined 1) whether rapid stimulus-specific learning occurs for unfamiliar, non-face stimuli in a texture identification task; 2) the effects of varying practice across a range from just 21 trials up to 840 trials; and 3) if rapid, stimulus-specific learning persists over a 1-week, as well as a 1-day, interval. Observers performed a texture identification task in two sessions separated by one day (Experiment 1) or 1 week (Experiment 2). Observers received varying amounts of practice (21, 63, 105, or 840 training trials) in session 1 and completed 840 trials in session 2. In session 2, one-half of the observers in each group performed the task with the same textures as in session 1, and one-half switched to novel textures (same vs.novel conditions). In both experiments we found that stimulus-specific learning - defined as the difference in response accuracy in the same and novel conditions - increased as a linear function of the log number of session 1 training trials and was statistically significant after approximately 100 training trials. The effects of stimulus novelty did not differ across experiments. These results support the idea that stimulus-specific learning in our task arises gradually and continuously through practice, perhaps concurrently with general learning.

The effects of stimulus novelty and negativity on BOLD activity in the amygdala, hippocampus, and bed nucleus of the stria terminalis.

The amygdala responds to stimulus novelty, which may correspond to an evaluation of novel stimuli for potential threat, and trait anxiety may modulate this response. The bed nucleus of the stria terminalis (BNST) may also be sensitive to novelty as it responds to both uncertainty and threat. If so, a BNST novelty response may also be affected by trait anxiety and interact with stimulus negativity. We presented participants with novel and repeated negative and neutral images while measuring brain activity via fMRI, and assessed participants’ self-reported trait anxiety. We expected to replicate past findings of novelty responses in the hippocampus and amygdala that are independent of stimulus negativity. We also expected BNST novelty-sensitivity and that trait anxiety would predict greater sensitivity to both novelty and negativity in the amygdala and BNST, but not the hippocampus. Our a priori analyses replicated past findings of a novelty response that was independent of valence in the hippocampus and amygdala. The BNST exhibited a novelty response for negative, but not neutral, images. Trait anxiety did not modulate the response to novelty or negativity in any of the ROIs investigated. Our findings suggest that the BNST plays a role in the detection of novelty. Key words: novelty; bed nucleus of the stria terminalis; BNST; amygdale; fMRI; BST

Novelty Enhancements in Memory Are Dependent on Lateral Prefrontal Cortex

Physiological evidence indicates that several brain regions, including the medial temporal lobes and prefrontal cortex (PFC), are involved in processing events that are novel or distinctive in their immediate context. However, behavioral studies that investigate whether these regions are critical for producing stimulus novelty advantages in memory are limited. For example, evidence from an animal lesion study indicated that the PFC is involved in stimulus novelty effects, but this has not been examined in humans. In the current study, we used a von Restorff novelty paradigm to test a large cohort of lateral PFC patients (n = 16). We found that patients with lateral PFC damage were impaired in recollection- and familiarity-based recognition, and they did not exhibit a normal memory advantage for novel compared with non-novel items. These results provide neuropsychological evidence supporting a key role for the lateral PFC in producing stimulus novelty advantages in memory.

The effects of stimulus novelty and familiarity on neuronal activity in the amygdala of monkeys performing recognition memory tasks

The function of the amygdala in behavioural responses to novel stimuli and its possible function in recognition memory were investigated by recording the responses of 659 amygdaloid neurons in monkeys performing recognition memory and visual discrimination tasks. The aim was to determine the contribution of the amygdala in the encoding of familiarity and therefore its role in supporting memory-related neuronal mechanisms in the basal forebrain. The responses of three groups of neurons reflected different forms of memory. One group (n = 10) responded maximally to novel stimuli and significantly less so to the same stimuli when they were familiar. The calculated memory spans of these neurons were in the range of 2-10 intervening trials, and this short-term retention of information may reflect the operation of a neural mechanism encoding memory for the recency of stimulus presentation. Two other groups responded to the sight of particular categories of familiar stimuli: to foods (n = 6) or to faces (n = 10). The responses of some of these stimulus-selective neurons declined with repeated presentations of foods (3/4 tests) and faces (2/6 tests). The activity of these latter two groups of neurons may be involved in behavioural responses to familiar visual stimuli, particularly when such stimuli have affective or motivational significance. We conclude that the neurophysiological data provide evidence of amygdaloid mechanisms for the recognition of recently seen visual stimuli. However, these amygdaloid mechanisms do not appear to be sufficient to support the performance of long-term recognition memory tasks without additional and complementary functions carried out by other ventromedial temporal, prefrontal and diencephalic structures which also project to the basal forebrain.

The orienting response: Stimulus factors and response measures

This paper outlines some of the basic ideas of the orienting response (OR) that have developed from the classical writings of E.N. Sokolov, in particular the effects of stimulus novelty, intensity, and significance upon the OR, and predictions about these effects on a range of physiological measures traditionally associated with the OR. Such measures include the GSR, respiration, heart rate, vascular responses, EEG, and pupil diameter. Unfortunately, many of the predictions of classical OR theory do not hold up when such a fine-grain analysis is undertaken. Possible conceptualizations of the discrepancies between Sokolovian predictions and empirical data are considered--should we accept such discrepancies as merely reflecting the imperfect nature of many OR indices, or seek other regularizing principles? Preliminary Process Theory has been proposed as one alternative account of the existing data base, and similarities and differences between it and Sokolovian theory are explored. The need for further investigation of such problems, in the very foundations of OR theory, appears to be of fundamental importance to the future status of the OR. An appendix provides a discussion between Barry and Sokolov on some of these issues.

S+ versus S− Fading in prompting procedures with autistic children

The purpose of this investigation was to assess the relative effectiveness of two prompt-fading procedures for teaching difficult visual discriminations to autistic children. Both prompt procedures involved within-stimulus fading where manipulation occurred on the relevant component of the discrimination. One procedure involved fading first along the S+ stimulus, while holding the S− stimulus constant. The other procedure involved fading first along the S− stimulus, while holding the S+ stimulus constant. Eight autistic children were each taught two discriminations, one by each of the prompt procedures. Results indicated that for all but one child, the discriminations were acquired significantly faster, with fewer errors, when the S+ stimulus was faded first. These findings are related to the literature on the effects of stimulus novelty on selection and learning.

Effects of stimulus novelty and dimensional saliency in human shift learning.

Effects of stimulus novelty and dimensional saliency in human shift learning.

Stimulus novelty effects during stimulus equivalence testing

An analysis is performed on the transfer test data from an experiment which factorially combines percent reward (50% vs 100%) and duration of confinement (2 vs 20 sec) in the presence of cue values from two redundant stimulus dimensions. Rats perform better on test trials which pair the previously negative cues with novel compound cues than on trials in which the previously positive cues are paired with a novel compound. Long confinement durations and partial reward during acquisition increase this difference. The results give further evidence that novelty affects test performance in single-dimensional transfer tests following redundant cue training.

Developmental Differences in the Effects of Stimulus Novelty on Discrimination Learning

Developmental Differences in the Effects of Stimulus Novelty on Discrimination Learning

Effects of stimulus novelty on gnawing and eating by rats.

Effects of stimulus novelty on gnawing and eating by rats.