Coding of hierarchical versus linear pattern structure in rats and humans.

In 3 Exps, rats and humans learned serial patterns composed of 24, 30, or 36 items. Patterns had a 2-, 3-, or 4-level hierarchical rule structure. In Exp 1 and 2, patterns had either perfect hierarchical structure or 2 modified chunks that violated hierarchical structure, thus producing linear structure. For both rats and humans, pattern structure predicted pattern learning difficulty and also the nature and relative frequency of errors. Both treated chunks that were inconsistent with hierarchical structure as violation chunks, and made errors that reflected their "tendency to regularize the perception of an irregular pattern" (F. Restle & B. L. Burnside, 1972). The results support the view that rats can abstract and encode a representation of multilevel hierarchical structure in serial patterns in much the same way as humans do in analogous tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Endoscopic transthoracic sympathectomy: an efficient and safe method for the treatment of hyperhidrosis

Rats learned serial patterns composed of either "run" chunks (e.g., 123 234 ...) or "trill" chunks (e.g., 121 232 ...). For each type of pattern, 1 group of rats encountered an element at the end of the pattern that violated the run or trill structure. In both run and trill patterns, violations were unusually difficult for rats to learn, whereas corresponding elements in "perfect" patterns that did not violate pattern structure were easy. Additionally, rats' errors on violation elements conformed to the structure of the patterns in which they were embedded. Thus, rats were sensitive to the run or trill organization of their patterns and mastered the rules governing the pattern before learning "exceptions to the rule."     

Sensitivity to violations of "run" and "trill" structures in rat serial-pattern learning.

Rats learned serial patterns composed of either "run" chunks (e.g., 123 234…) or "trill" chunks (e.g., 121 232…). For each type of pattern, 1 group of rats encountered an element at the end of the pattern that violated the run or trill structure. In both run and trill patterns violations were unusually difficult for rats to learn, whereas corresponding elements in "perfect" patterns that did not violate pattern structure were easy. Additionally, rats' errors on violation elements conformed to the structure of the patterns in which they were embedded. Thus, rats were sensitive to the run or trill organization of their patterns and mastered the rules governing the pattern before learning "exceptions to the rule." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Artificial grammar learning depends on implicit acquisition of both abstract and exemplar-specific information.

The contributions of exemplar-specific and abstract knowledge to artificial grammar learning were examined in amnesic patients and controls. In Experiment 1, grammatical rule adherence and chunk strength exerted separate effects on grammaticality judgments. Amnesic patients exhibited intact classification performance, demonstrating the same pattern of results as controls. In Experiment 2, amnesic patients exhibited impaired declarative memory for chunks. In Experiment 3, both amnesic patients and controls exhibited transfer when tested with a letter set different than the one used for training, although performance was better when the same letter sets were used at training and test. The results suggest that individuals learn both abstract information about training items and exemplar-specific information about chunk strength and that both types of learning occur independently of declarative memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Artificial grammar learning depends on implicit acquisition of both abstract and exemplar-specific information": Correction.

Reports an error in the original article by B. J. Knowlton and L. R. Squire (Journal of Experimental Psychology: Learning, Memory, and Cognition, Vol 22[1], 169–181). The Appendix on page 181 contains several errors. The corrected Appendix is provided. (The following abstract of this article originally appeared in record 1996-02680-010). The contributions of exemplar-specific and abstract knowledge to artificial grammar learning were examined in amnesic patients and controls. In Experiment 1, grammatical rule adherence and chunk strength exerted separate effects in grammaticality judgments. Amnesic patients exhibited intact classification performance, demonstrating the same pattern of results as controls. In Experiment 2, amnesic patients exhibited impaired declarative memory for chunks. In Experiment 3, both amnesic patients and controls exhibited transfer when tested with a letter set different than the one used for training, although performance was better when the same letter sets were used at the training and test. The results suggest that individuals learn both abstract information about training items and exemplar-specific information about chunk strength and that both types of learning occur independently of declarative memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resistance to change within heterogeneous response sequences.

Three experiments investigated how instrumental and Pavlovian contingencies contribute to resistance to change (RTC) in different ordinal response positions within heterogeneous response sequences in pigeons. RTC in the initial and terminal response positions of a three-response sequence were compared in Experiment 1, which presented three colored key lights in succession in each trial; and in Experiment 2, which severely degraded Pavlovian contingencies by presenting the lights simultaneously at each ordinal position. Experiment 3 eliminated the instrumental contingency in a high-order sign-tracking procedure. When the instrumental contingency was in effect, RTC of the initial position was greater than the terminal position (Initial RTC > Terminal RTC) when the Pavlovian contingencies were strong and when they were degraded. When the instrumental contingency was eliminated, RTC patterns reversed, producing a graded pattern of RTC (Initial     

Dissociations of grammaticality and specific similarity effects in artificial grammar learning.

Three artificial grammar learning experiments investigated the memory processes underlying classification judgments. In Experiment 1, effects of grammaticality, specific item similarity, and chunk frequency were analogous between classification and recognition tasks. In Experiments 2A and 2B, instructions to exclude "old" and "similar" test items, under conditions that limited the role of conscious recollection, dissociated grammaticality and similarity effects in classification. Dividing attention at test also produced a dissociation in Experiment 3. It is concluded that a dual-process model of classification, whereby the grammaticality and specific similarity effects are based mostly on automatic and intentional memory processes, respectively, is consistent with the results, whereas a unitary mechanism account is not. This conclusion is further supported by evidence indicating that chunk frequency had both implicit and explicit influences on classification judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Phrasing cues and hierarchical organization in serial pattern learning by rats.

In Exp I, 42 female albino Sprague-Dawley rats received food quantities in a T-maze in a serial pattern. Ss learned under either no cue, temporal cue, place cue, and/or combined temporal-place cue conditions. In Exp II, 45 female albino Sprague-Dawley rats in the T-maze were trained in complex subpatterns with place cues or no cues. Exp I showed that phrasing facilitated pattern learning as long as phrasing cues were available but that Ss learned different things when different kinds of phrasing cues were used. Exp II showed that phrasing a pattern into formally complex rather than formally simple chunks produced poor learning. Overall findings demonstrate the rat's capacity to abstract and use higher-order rules in hierarchical serial patterns, especially when phrasing cues are available to facilitate the process. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two mechanisms in implicit artificial grammar learning? Comment on Meulemans and Van der Linden (1997).

T. Meulemans and M. Van der Linden (see record 1997-05320-013) presented evidence for 2 distinct mechanisms involved in artificial grammar learning. They suggested that after training on 32 letter strings (Experiment 2A), participants classify test strings using knowledge of the distributional statistics of letter chunks, whereas after training on 125 letter strings (Experiment 2B) they classify on the basis of knowledge of the rules of the grammar. This article offers an alternative unitary account of Meulemans and Van der Linden's findings. The authors show that information about grammatical rules and chunk locations was confounded in the test strings used in Experiment 2B and then present evidence that all of the data can be explained in terms of distributional knowledge, provided this includes knowledge of the positional constraints on chunks. Finally, the authors question the utility of traditional finite-state grammars for investigating abstraction processes, and suggest alternative methods. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic and controlled components of judgment and decision making.

The categorization of inductive reasoning into largely automatic processes (heuristic reasoning) and controlled analytical processes (rule-based reasoning) put forward by dual-process approaches of judgment under uncertainty (e.g., K. E. Stanovich & R. F. West, 2000) has been primarily a matter of assumption with a scarcity of direct empirical findings supporting it. The present authors use the process dissociation procedure (L. L. Jacoby, 1991) to provide convergent evidence validating a dual-process perspective to judgment under uncertainty based on the independent contributions of heuristic and rule-based reasoning. Process dissociations based on experimental manipulation of variables were derived from the most relevant theoretical properties typically used to contrast the two forms of reasoning. These include processing goals (Experiment 1), cognitive resources (Experiment 2), priming (Experiment 3), and formal training (Experiment 4); the results consistently support the author's perspective. They conclude that judgment under uncertainty is neither an automatic nor a controlled process but that it reflects both processes, with each making independent contributions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of medial prefrontal or anterior cingulate cortex lesions on responding for cocaine under fixed-ratio and second-order schedules of reinforcement in rats

Four experiments examined the effects of excitotoxic, axon-sparing lesions of the medial prefrontal cortex or anterior cingulate cortex in rats on responding under different schedules of intravenous cocaine self-administration and on the locomotor stimulant effects of cocaine. Experiment 1 tested the acquisition and maintenance of cocaine self-administration under a fixed ratio schedule. Rats with medial prefrontal cortex lesions showed facilitated acquisition and enhanced responding for low doses of the drug when lesions were induced before self-administration behaviour was established. Lesions of the anterior cingulate cortex did not affect cocaine self-administration. In experiment 2, rats were trained to respond under a second-order schedule of cocaine reinforcement, where responding during the fixed interval was reinforced by presentation of a cocaine-associated visual stimulus under fixed-ratio contingencies. In control rats, these schedule conditions were found to maintain high rates of responding and a scalloped pattern of responding over time. Omission of conditioned stimulus presentation during the fixed interval significantly disrupted response patterns, confirming that the stimulus served to maintain responding during the fixed interval. By contrast, rats with medial prefrontal cortex lesions showed higher rates and disrupted patterns of responding that were unchanged by stimulus omission. Rats with lesions of the anterior cingulate cortex responded at high rates throughout the fixed interval under all test conditions, indicating that the cocaine-associated stimulus did not serve to maintain temporal patterns of responding in these rats. Experiment 3 demonstrated the lack of effect of either lesion on the acquisition of responding for a non-drug reinforcer, sucrose. In experiment 4, measures of spontaneous and cocaine-induced locomotor activity revealed that rats in both lesion groups were significantly more active than controls regardless of test conditions. These data indicate that facilitated acquisition of cocaine self-administration and disrupted response patterns under second-order schedule contingencies may result from deficits in behavioural inhibition induced by medial prefrontal cortical lesions that contrast with deficits following damage to other limbic cortical regions, such as the basolateral amygdala or anterior cingulate cortex.     

Comparison of the interoceptive sensory consequences of CCK, LiCl, and satiety in rats.

In three experiments we assessed the degree to which ad lib feeding, injection of cholecystokinin (CCK), and injection of lithium chloride (LiCl) produce states with similar sensory consequences. In each experiment, two groups of rats were trained to use cues arising from food deprivation and satiation of discriminative signals for shock. One group was shocked when deprived but not when nondeprived. The other group received the reversed discrimination. Testing began when incidence of freezing was greater under the shocked deprivation than under the nonshocked deprivation condition. In Experiment 1, the rats were tested under 24-hr food deprivation after injections of CCK, LiCl, and saline (in counterbalanced order). The effects of CCK on freezing did not differ from those of saline, whereas both CCK and LiCl had effects that were different from ad lib feeding. This pattern of results was also obtained when deprivation level during training and testing was reduced to 8 hr (Experiment 1A) and also when rats received small amounts of food in conjunction with CCK (Experiment 2). The intubation of a high-calorie stomach load (Experiment 1A) produced a response profile like that observed after free feeding. Freezing after LiCl treatment differed from that observed after free feeding and from that found after injection of CCK. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Blocking in rat serial pattern learning.

Both associative and rule-learning theories have been proposed to account for rat serial pattern learning, but individually they are unable to account for a variety of recent behavioral and psychobiological phenomena. The present study examined the role of rule learning versus discriminative learning in rat pattern learning using a classic associative phenomenon: blocking. Rats learned to press levers in an 8-lever circular array according to a rule-based serial pattern, 123–234–345–456–567–678–781–812, where digits indicate the correct lever in the array for each trial. Each pattern presentation contained a chunk with a final element violation, such as 454 instead of 456. Rats learned in a first phase that a noise signaled the violation chunk; then, a concurrent spatial cue was added in a second phase. A test with spatial cues alone showed that blocking occurred. The results suggest that associative learning mediated cuing of violation elements. Taken together with other behavioral and psychobiological evidence already reported in the literature implicating rule learning when rats learn this pattern in this paradigm, these results implicate multiple concurrent learning processes in rat serial pattern learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquisition, retention, and extinction of operant discriminations in rats with nucleus basalis magnocellularis lesions.

Effects of bilateral ibotenic acid lesions of nucleus basalis magnocellularis (NBM) and scopolamine treatment on different aspects of learning and memory in an operant discrimination task were assessed. In Experiment 1, NBM lesions impaired acquisition performance. In Experiment 2, scopolamine lowered response rates but did not affect discrimination accuracy in lesioned or control rats. In Experiment 3, although pretrained rats showed transient increases in commission errors, percentage correct responding remained above chance levels after lesion. During extinction in Experiment 4, operant responding diminished more quickly in pretrained NBM-lesioned rats than in controls, but subsequent reacquisition performance was equivalent in both groups. Results suggest the NBM is importantly involved in discrimination learning, but cholinergic activity may be less critical for memory retention than for acquisition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Syllable chunking in zebra finch (Taeniopygia guttata) song.

Examined how 61 young zebra finch males copied song from 5 adult tutors. Zebra finch song consists of a string of 5–25 distinct syllables, and these syllables were copied as chunks, or strings of consecutive syllables (modal length?=?3). The silent interval between 2 syllables was copied as part of the syllable after the silence. Copied chunks had boundaries that fell at consistent locations within the tutor's song, marked by a relatively long intersyllable silent period, a transition between call-like and noncall-like syllables, and a tendency for the tutor male to stop his song short. Young males also tended to break their songs off at the bondaries of the chunks they had copied. Chunks appear to be an intermediate level of hierarchy in song organization and to have both perceptual (syllables were learned as part of a chunk) and motor (song delivery was broken almost exclusively at chunk boundaries) aspects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial patterns in the control of human arm movement

Generalized Procrustes analysis was used to investigate the spatial paths of pointing movements. In Experiment 1, 3 participants produced similar spatial paths of the hand when repeating a pointing movement many times, despite variability in the position and orientation of the movements. The average spatial path indicates a fundamental spatial pattern of the motor system, or motor primitive. This pattern varied across the workspace. Anterioposterior movements were straight, but repeated movements had variable spatial patterns. Lateral movements were curved away from the body but had regular spatial patterns. Experiment 2 extended these results to movements of different amplitudes in 7 participants. The motor primitive seems to be abandoned at the end of the movement in favor of final adjustments to bring the hand to the target position. In Experiment 3, the same participants produced similar motor primitives both with and without vision.     

TRACX: A recognition-based connectionist framework for sequence segmentation and chunk extraction.

Individuals of all ages extract structure from the sequences of patterns they encounter in their environment, an ability that is at the very heart of cognition. Exactly what underlies this ability has been the subject of much debate over the years. A novel mechanism, implicit chunk recognition (ICR), is proposed for sequence segmentation and chunk extraction. The mechanism relies on the recognition of previously encountered subsequences (chunks) in the input rather than on the prediction of upcoming items in the input sequence. A connectionist autoassociator model of ICR, truncated recursive autoassociative chunk extractor (TRACX), is presented in which chunks are extracted by means of truncated recursion. The performance and robustness of the model is demonstrated in a series of 9 simulations of empirical data, covering a wide range of phenomena from the infant statistical learning and adult implicit learning literatures, as well as 2 simulations demonstrating the model's ability to generalize to new input and to develop internal representations whose structure reflects that of the items in the input sequence. TRACX outperforms PARSER (Perruchet & Vintner, 1998) and the simple recurrent network (SRN, Cleeremans & McClelland, 1991) in matching human sequence segmentation on existing data. A new study is presented exploring 8-month-olds' use of backward transitional probabilities to segment auditory sequences. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

On the costs of accessible attitudes: Detecting that the attitude object has changed.

The present research examined whether individuals with more accessible attitudes have more difficulty detecting that the attitude object has changed. While being repeatedly exposed to photographs of undergraduates, participants either rehearsed their attitudes toward each photo or performed a control task. They then saw these original photos and computer-generated morphs representing varying degrees of change in an original. Participants in the attitude rehearsal condition required more time to correctly identify morphs that were similar to the original as "different" (Experiment 1) and made more errors in response to such morphs (Experiment 2). Experiment 3 revealed that participants with accessible attitudes perceived relatively less change; they were less likely to view a morph as a photo of a novel person and more likely to view it as a different photo of a person seen before. The costs and benefits of accessible attitudes are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Correction to Rotton, Tikofsky, and Feldman.

Reports an error in the original article by Rotten et al (Journal of Applied Psychology. Vol 67(2) Apr 1982, 230-238). The receipt date was incorrectly listed as May 11, 1982. The article was actually received on May 11, 1981.(The following abstract of this article originally appeared in record 1982-20688-001) In Exp I, 42 Ss (mean age 30.4 yrs) tracked a moving target and monitored lights after receiving sublingual drops that contained either water, sodium nitrate (4.5, 45, 450, or 4,500 ppm), or sodium fluoride (.1, 1, 10, or 100 ppm). Dosage levels equaled, exceeded, or fell below those of municipal waters. In Exp II, 20 females performed this task after receiving sublingual drops of the same test substances in a repeated measures design; dosage levels equaled or exceeded levels found in municipal waters by 100 or 500 times. Neither type nor amount of chemical affected primary task performance; however, after receiving sublingual drops in Exp I, Ss paid less attention to lights on their right. In Exp II, Ss made more errors and had longer response latencies after they received moderate and very high concentrations of test substances. It is concluded that challenge testing is a safe but effective technique for provoking and studying reactions to chemicals when combined with a sensitive measure of sensorimotor performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)