Achievement of specificational information usage with true and false feedback in learning a visual relative-mass discrimination task.

Participants' usage of informational variables in learning visual relative-mass discrimination in collisions was tracked by means of PROBIT correlations. Four groups received feedback that was true or accorded with either of three nonspecificational cue variables. A majority in each group adopted the feedback, but several participants defied the false feedback. Unlike in previous research, the fit to data of the relative-mass invariant could not be bettered by post hoc linear combinations of the cues. Discriminability was lower in the use of the invariant. Analytic complexity was rejected as an explanation for discriminability differences. A "smart mechanism" for pickup of the relative-mass invariant was developed as an extension of G. Johansson's (1950/1994) vector model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of visual and nonvisual feedback in a vehicle steering task.

This article investigates vehicle steering control, focusing on the task of lane changing and the role of different sources of sensory feedback. Participants carried out 2 experiments in a fully instrumented, motion-based simulator. Despite the high level of realism afforded by the simulator, participants were unable to complete a lane change in the absence of visual feedback. When asked to produce the steering movements required to change lanes and turn a corner, participants produced remarkably similar behavior in each case, revealing a misconception of how a lane-change maneuver is normally executed. Finally, participants were asked to change lanes in a fixed-based simulator, in the presence of intermittent visual information. Normal steering behavior could be restored using brief but suitably timed exposure to visual information. The data suggest that vehicle steering control can be characterized as a series of unidirectional, open-loop steering movements, each punctuated by a brief visual update. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stress reduces use of negative feedback in a feedback-based learning task.

In contrast to the well-established effects of stress on learning of declarative material, much less is known about stress effects on reward- or feedback-based learning. Differential effects on positive and negative feedback especially have received little attention. The objective of this study, thus, was to investigate effects of psychosocial stress on feedback-based learning with a particular focus on the use of negative and positive feedback during learning. Participants completed a probabilistic selection task in both a stress and a control condition. The task allowed quantification of how much participants relied on positive and negative feedback during learning. Although stress had no effect on general acquisition of the task, results indicate that participants used negative feedback significantly less during learning after stress compared with the control condition. An enhancing effect of stress on use of positive feedback failed to reach significance. These findings suggest that stress acts differentially on the use of positive and negative feedback during learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Retention interval and intertrial interval in a serial learning or delayed discrimination task.

In 4 experiments, 58 male albino rats were provided with the same 3-event decreasing series (18-1-0) of food pellets in a runway to investigate tracking—running fast to 18 pellets and running slow to 1 and 0 pellets. Results show that when more than 1 daily trial was given, tracking was acquired more slowly and was disrupted by a shift in retention interval from 15 sec to 5 min. Tracking was also disrupted by a shift from 1 to 2 trials each day. Results indicate that when given 1 18-1-0 trial each day, Ss partitioned events on a 1st-event/subsequent-event basis, that little forgetting occurred even at long retention intervals, that somewhat different memories signaled events when 1 or more than 1 18-1-0 trial occurred each day, and that retention interval deficits could arise owing to the same or similar memories' signaling different events. Results limit the generality of 3 hypotheses suggested by H. L. Roitblat (see record 1983-09709-001) and by S. J. Haggbloom and M. W. Ekdahl (1985): that as retention interval increases, rats find it increasingly difficult to remember and utilize serial position cues; that tracking in serial tasks is not influenced by number of trials each day; and that there are specific stimuli associated with each retention interval that when changed, necessarily disrupt performance. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sleep-dependent learning and practice-dependent deterioration in an orientation discrimination task.

Learning new information requires practice. The degree of learning can be influenced by the amount of practice and whether subjects sleep between sessions. Over-practice, however, can lead to performance deterioration. The interaction between practice-dependent deterioration and sleep-dependent learning needs more study. We examine whether the amount of practice before sleep alters learning, and whether prior sleep protects against deterioration. Two groups (N = 33) were tested three times across two days on an orientation discrimination task. The High practice group was tested twice before a night of sleep and once after, at 9 a.m., 7 p.m., and 9 a.m. The Low practice group was tested once before a night of sleep and twice after, at 7 p.m., 9 a.m., and 7 p.m. Overall, both groups showed (1) deterioration with repeated, within-day testing, (2) performance improvement only after a night of sleep, (3) similar amounts of sleep-dependent learning and practice-dependent deterioration. In summary, we found that sleep resets visual contrast thresholds to a lower baseline (i.e., produces learning), but does not prevent over-practice deterioration effects. Likewise, over-practice deterioration does not influence the magnitude of overnight learning on this task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquired equivalence in human discrimination learning: The role of propositional knowledge.

The current study investigated the role of propositional knowledge in human acquired equivalence effects. Across 5 experiments, human adults were trained to associate different visual stimuli. Subsequent procedures presented training that was either consistent or inconsistent with the previous associations. More accurate responding in the consistent versus inconsistent condition reflected an acquired equivalence effect. The results of Experiment 1 indicated that a previously reported divergence between verbal and associative processes was likely due to instructional control. Experiments 2-5 further examined the role of verbal processes and demonstrated that acquired equivalence may be produced with verbal instructions alone and critically through a combination of instructions and actual stimulus pairings. The current data not only challenge a purely associative account but actively support an interaction between verbal and associative processes in producing the acquired equivalence effect in humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of information about the response-outcome relation in instrumental discrimination learning.

In 4 instrumental learning experiments, the hierarchical organization among responses (R), outcomes (O), and stimuli (ST) was examined. Each experiment explored the possibility that ST becomes associated with the R–O relation by providing information about that relation. In each case, an analogy was developed to a paradigm that has been important for concluding that informational relations affect Pavlovian conditioning. Experiments 1 and 2 found an effect of the information that ST provide about the R–O relation, using paradigms analogous to blocking and contingency experiments. Experiments 3 and 4 demonstrated a similar result, using a paradigm like that of relative validity. In each case, the experiments pointed to the importance of the information that ST give about the R–O relation, rather than about the individual R and O elements. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of frequency of feedback on a simple coaction task.

Used a learned drive approach to predict the effects of feedback on a coaction task; 60 female undergraduates were Ss. It was hypothesized that the magnitude of social facilitation would be greater the more often Ss were given feedback of their own or the other coactor's performance. The frequency of feedback was manipulated by varying the number of responses required to produce a tone. Coactors received a tone after every 4 (FR4) or 7 (FR7) responses and performed in the presence of another person who was either on an FR4 or an FR7 schedule. To furnish a comparison to the coaction conditions, some Ss were tested individually on an FR4 and others on an FR7 schedule. Within the coaction conditions, the most responding occurred when both Ss received an FR4 schedule, and the fewest responses when both coactors were on an FR7 schedule. An intermediate number of responses was produced when one coactor was on an FR4 and the other on an FR7 schedule. Also, Ss working in coaction conditions responded more than those performing alone. (9 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditional discrimination learning by pigeons: The role of simultaneous versus successive stimulus presentations.

A series of experiments investigated the development of a conditional discrimination involving a blue or red keylight and a subsequently presented vertical or horizontal line. Pigeons trained in a single reversal paradigm failed to learn the conditional task despite manipulations that assured continued attention to the colors by reinforcing responding to them and other manipulations that reduced both the short-term and long-term memory requirements inherent in the task. If the colors both preceded and overlapped the lines, the Ss learned a conditional discrimination, but it involved only the overlapping component of the color and the lines. The sequential conditional discrimination was acquired only when training involved frequent reversals. The difficulty of learning a sequential conditional discrimination, relative to a simultaneous one, presumably reflects the true hierarchical nature of the task; simultaneous conditional tasks are not necessarily hierarchical. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A reexamination of the concurrent discrimination learning task: The importance of anterior inferotemporal cortex, area TE.

For 30 years, the concurrent discrimination learning task has figured prominently in studies used to determine the effects of medial temporal lobe damage in monkeys. However, the findings from these studies have been contradictory. We explored the contribution to concurrent discrimination performance of inadvertent damage to area TE by reexamining the behavioral data and histological material from monkeys with medial temporal lobe lesions previously tested in our laboratory. The amount of inadvertent damage to area TE was more predictive of impaired performance on the concurrent discrimination learning task than was the amount of damage to any medial temporal lobe structure, including the perirhinal cortex. These findings resolve earlier inconsistent findings regarding the concurrent discrimination learning task by demonstrating that performance on this task depends on area TE and not on perirhinal cortex or other medial temporal lobe structures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of perinatal pathologies in premature neonates using a syllable discrimination task

OBJECTIVE: To determine the preferred treatment of clinically localized prostate cancer. DESIGN: Cancer grade, patient age, and comorbidities are considered in a Markov model with Monte Carlo sensitivity analyses. Large and recent pooled analyses and patient-derived utilities are included. RESULTS: Principal findings suggest benefit for radical prostatectomy relative to watchful waiting for men under 70 years of age with low to moderate comorbidity. Men older than 70 with high comorbidity and disease of low to moderate grade do better with watchful waiting. CONCLUSIONS: Cohort-level sensitivity analyses suggest a quality-based treatment benefit for radical prostatectomy for younger men and treatment harm for older men. Tailored patient and clinician decisions remain necessary, especially for men older than 70 in good health but with aggressive cancers.     

The role of error density and set in a vigilance task.

To study ability to detect certain signals while persistently looking for them, 216 students were involved in proofreading tasks. Results were sought pertaining to error detection as a function of error density, false detections at various error levels, influence of previous density on present detection, and false detections after shifts in error density. All vigilance tasks may be subject to decreasing efficiency at extremely high error levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Life span changes in visual enumeration: The number discrimination task.

Participants from 5 groups with mean ages of 6, 8, 10, 22, and 72 yrs were tested on a series of speeded number discriminations: 1 vs 2, 3 vs 4, 6 vs 7, and 8 vs 9. The primary measure of interest (response time slope as a function of number size) decreased with age for numbers in the 1–4 range. However, a U-shaped age function emerged in the 6–9 range, with larger slopes for children and senior adults, and the smallest slopes for young adults. These data suggest that different processes are involved in enumerating small and large numbers of items. It is argued that subitizing, the process for small numbers, makes only minimal demands on spatial attention and thus shows developmental improvements without any decline in old age. In contrast, counting, the process for large numbers, requires sophisticated coordination of spatial attention, which has previously been shown first to improve and then decline over the life span. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of attention in a spatial memory task in Alzheimer disease patients

Memory and attention are interrelated cognitive processes that most likely influence the functioning of each other, yet they are often difficult to distinguish in psychological experiments. Young, aged adults, and patients with Alzheimer disease (AD) were tested on a delay response task measuring spatial memory that also placed high demands on attentional resources. Aged adults performed as well as young, suggesting that neither attentional nor memory abilities were exceeded in either group. However, AD subjects were severely impaired on this task. Two further experiments with AD patients examined the relative contribution of attentional and memory deficits in the performance of this population. Both memory and attentional impairments were found; however, errors due to memory factors were more closely related to severity of disease as measured on the Folstein Mini-Mental State Examination than were errors of attentional origin. These studies demonstrate the necessity of accounting for attentional components in studies examining memory, especially in patients with AD.     

Cholinergic drug effects on a delayed conditional discrimination task in the rat

The centrally acting cholinergic antagonist scopolamine (0.025-0.10 mg/kg ip) and the peripherally acting cholinergic antagonist methyl-scopolamine (0.01-0.10 mg/kg) dose dependently impaired discriminability independent of delay in a delayed conditional discrimination task that precludes use of mediating behavior. This indicates that scopolamine does not specifically affect working memory. Drugs that enhance cholinergic transmission neither improved discriminability nor attenuated scopolamine-induced impairments. In a post hoc analysis scopolamine was found to impair discriminability in a delay-dependent manner in rats that performed at a high level in pretest sessions. Methyl-scopolamine impaired performance independently of delay in these rats. The authors suggest that a ceiling effect at short delays produced this Drug x Delay interaction of scopolamine in the best performing rats.     

Effects of pimozide on escape and discrimination performance in a water-escape task.

Three experiments studied the effects of pimozide (0.2 and 0.4 mg/kg) on discrimination learning of 255 male CD1 mice in a water-escape paradigm in which the degree of motor difficulty was manipulated by varying water temperature. The drug marginally affected escape latencies in relatively warm water (25°C) but markedly disrupted escape latencies when the task was more demanding (e.g., 15 and 20°C water). The escape deficits, however, were not accompanied by disturbances in the acquisition of position discrimination or cue discrimination responses when Ss were required to make the highly prepared response of swimming to light or the contraprepared response of swimming to dark. Data suggest that in tasks involving aversive motivation, pimozide influences performance through its effects on response maintenance but does not appear to affect either associative or motivational processes. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Configural associations in discrimination learning.

In 4 experiments, Sprague-Dawley rats and homing pigeons received training with an A+ AB0 BC+ discrimination, in which food (+) accompanied trials with A and BC. Food was not presented (0) on trials with the compound AB. Subsequent test trials revealed that responding during C by itself, or the compound ABC, was slower than during either A or BC. Responding during the ABC compound was also found to be slower after training with the A+ AB0 BC+ than an A0 AB+ BC+ discrimination. We argue that these findings demonstrate the importance of configural associations in discrimination learning. Two accounts for the way in which these associations exert their influence are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of response selection for inhibition of task sets in task shifting.

Response selection in task shifting was explored using a go/no-go methodology. The no-go signal occurred unpredictably with stimulus onset so that all trials required task preparation but only go trials required response selection. Experiment 1 showed that shift costs were absent after no-go trials, indicating that response processes are crucial for shift costs. In Experiment 2, backward inhibition was absent after no-go trials. Experiments 3 and 4 demonstrated that response selection, rather than execution, causes backward inhibition. All 4 experiments showed effects of preparation time in go trials, suggesting that advance preparation must have also occurred in no-go trials. The authors concluded that inhibition of irrelevant task sets arises only at response selection and that residual shift costs reflect such persisting inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of response repetition in task switching.

When switching between tasks, participants are sometimes required to use different response sets for each task. Thus, task switch and response set switch are confounded. In 5 experiments, the authors examined transitions of response within a linear 4-finger arrangement. A random baseline condition was compared with the cuing of specific response subsets grouped by hand or by finger equivalence, and these subsets were examined in both single task and task-switching designs. Results showed that part of the task switch cost is associated with switching between response sets. Furthermore, the analysis revealed a novel effect: When task switching and repetition trials are mixed, a bias towards switching the response and/or hand is found in task repetition trials. Response repetition is hindered when a task switch is expected, even for those trials when a switch of task does not occur. The results demonstrate executive processes involved in task set configuration closely depend on the motoric processing of the response set. The results are also important for current theories of task set control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of response-produced and exteroceptive feedback in the attenuation of fear over the course of avoidance learning.

Possible mechanisms mediating fear attenuation over prolonged avoidance learning were examined. In Replication 1, two groups of rats (masters) received 50 or 200 trials of signaled avoidance training. Six groups were yoked to each master group: Three were strictly yoked, and three were yoked only for reinforced conditioned stimulus (CS) presentations (yoked fear conditioning). Of the six groups, two (one strictly yoked and one yoked fear conditioning) received exteroceptive feedback contingent upon the reponses of the masters, two received random/noncontingent feedback, and two received no feedback. Fear of the conditioned stimulus (CS), indexed by freezing during the CS, was lowest in the 200-trial masters and in the two 200-trial groups receiving contingent feedback. In Replication 2, which was procedurally identical to Replication 1 except that the master groups received contingent exteroceptive feedback, fear was lowest in the same three groups. These results support the conclusion that the response-produced feedback that an avoidance response provides is responsible for the fear attenuation seen in well-trained avoidance responders. Several hypotheses concerning the effects of feedback in mediating fear attenuation are examined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)