Criterion Level Of Performance Research Articles

Auditory Deprivation during Development Alters Efferent Neural Feedback and Perception.

Auditory experience plays a critical role in hearing development. Developmental auditory deprivation because of otitis media, a common childhood disease, produces long-standing changes in the central auditory system, even after the middle ear pathology is resolved. The effects of sound deprivation because of otitis media have been mostly studied in the ascending auditory system but remain to be examined in the descending pathway that runs from the auditory cortex to the cochlea via the brainstem. Alterations in the efferent neural system could be important because the descending olivocochlear pathway influences the neural representation of transient sounds in noise in the afferent auditory system and is thought to be involved in auditory learning. Here, we show that the inhibitory strength of the medial olivocochlear efferents is weaker in children with a documented history of otitis media relative to controls; both boys and girls were included in the study. In addition, children with otitis media history required a higher signal-to-noise ratio on a sentence-in-noise recognition task than controls to achieve the same criterion performance level. Poorer speech-in-noise recognition, a hallmark of impaired central auditory processing, was related to efferent inhibition, and could not be attributed to the middle ear or cochlear mechanics.SIGNIFICANCE STATEMENT Otitis media is the second most common reason children go to the doctor. Previously, degraded auditory experience because of otitis media has been associated with reorganized ascending neural pathways, even after middle ear pathology resolved. Here, we show that altered afferent auditory input because of otitis media during childhood is also associated with long-lasting reduced descending neural pathway function and poorer speech-in-noise recognition. These novel, efferent findings may be important for the detection and treatment of childhood otitis media.

Dynamics and Hierarchical Encoding of Non-compact Acoustic Categories in Auditory and Frontal Cortex.

Categorical perception is a fundamental cognitive function enabling animals to flexibly assign sounds into behaviorally relevant categories. This study investigates the nature of acoustic category representations, their emergence in an ascending series of ferret auditory and frontal cortical fields, and the dynamics of this representation during passive listening to task-relevant stimuli and during active retrieval from memory while engaging in learned categorization tasks. Ferrets were trained on two auditory Go-NoGo categorization tasks to discriminate two non-compact sound categories (composed of tones or amplitude-modulated noise). Neuronal responses became progressively more categorical in higher cortical fields, especially during task performance. The dynamics of the categorical responses exhibited a cascading top-down modulation pattern that began earliest in the frontal cortex and subsequently flowed downstream to the secondary auditory cortex, followed by the primary auditory cortex. In a subpopulation of neurons, categorical responses persisted even during the passive listening condition, demonstrating memory for task categories and their enhanced categorical boundaries.

Response: Commentary: Perceptual learning in autism: over-specificity and possible remedies.

In a recent study, we tested perceptual learning in adults with autism spectrum disorder (ASD) (Harris et al., 2015), employing the standard and well-established texture-learning paradigm [TDT; (Karni and Sagi, 1991; Sagi, 1995; Harris et al., 2012)]. In this paradigm, observers learn to discriminate an oriented texture target embedded at a fixed location in a background of elements having a different orientation. Performance is measured as a function of the time-interval between the onset of the target and a mask (stimulus onset asynchrony, SOA), with threshold defined as the minimal time (SOA) to reach a predefined criterion level of performance. Typical observers improve their performance (show reduced thresholds) with training across 3–4 days, but need to relearn the task when the target is moved to a different location in the visual field, showing specificity. We (Harris et al., 2015) reported similar results with observers with ASD, but unlike the typical observers who showed faster learning at the second location (Sagi, 2011), ASD observers showed difficulty in relearning the task at the second location, suggesting that the training with the target at the first location might have interfered with the training at the new, second location. We termed this anomalous poor learning “over-specificity” (OS) to reflect the narrowness of the learning and the failure to generalize, and quantified OS as the average threshold difference between the second and the first learning curves (for generalization OS 0). A modified learning paradigm, where standard target trials were interleaved with no-target trials (“dummy” trials) during training, showed generalization of learning (OS 1) has never been observed before.

Cues for auditory stream segregation of birdsong in budgerigars and zebra finches: Effects of location, timing, amplitude, and frequency.

Deciphering the auditory scene is a problem faced by many organisms. However, when faced with numerous overlapping sounds from multiple locations, listeners are still able to attribute the individual sound objects to their individual sound-producing sources. Here, the characteristics of sounds important for integrating versus segregating in birds were determined. Budgerigars and zebra finches were trained using operant conditioning procedures on an identification task to peck one key when they heard a whole zebra finch song and to peck another when they heard a zebra finch song missing a middle syllable. Once the birds were trained to a criterion performance level on those stimuli, probe trials were introduced on a small proportion of trials. The probe songs contained modifications of the incomplete training song's missing syllable. When the bird responded as if the probe was a whole song, it suggests they streamed together the altered syllable and the rest of the song. When the bird responded as if the probe was a non-whole song, it suggests they segregated the altered probe from the rest of the song. Results show that some features, such as location and intensity, are more important for segregating than other features, such as timing and frequency.

Using embedded instruction to teach functional skills to a preschool child with autism

Objectives: Integration of children’s individualized behavioral learning objectives into ongoing activities, routines, and transitions of preschool classrooms has been a recommended practice for many years in the field of early childhood special education. This study examined the effectiveness of embedded instruction in teaching three functional skills to a child with autism enrolled in a preschool classroom specifically designed for children with autism.Methods: A multiple probe design was used to evaluate the effects of embedded instruction on skill acquisition and maintenance.Results: Results showed that the child learned all three target behaviors and maintained high levels of independent performance during follow-up sessions conducted 1–8 weeks after the child reached criterion level of performance for a behavior. Moreover, preschool teachers who observed the intervention sessions reported that the intervention was appropriate, easy to use, and beneficial to the participating child.Conclusion: These findings along with the findings of previous research suggest that embedded instruction may offer viable and effective ways to provide intentional, systematic, and individualized instruction and interventions to young children with autism within ongoing activities, routines, and transitions of early childhood settings. Implications for practice and future research are discussed.

Production and integrated training of adjectives in three individuals with nonfluent aphasia

Background: Current research in theoretical linguistics, experimental psychology, and clinical aphasiology suggests that adjective training may facilitate unique aspects of language production and functional communication in persons with aphasia. Although considerable research has been devoted to treatments targeting nouns and verbs, there has been relatively little treatment research directed towards adjectives.Aims: The goal of this study was to further investigate the viability of adjective training in aphasia by applying an integrated treatment approach targeting adjective production in the context of single word, sentence, and discourse levels of communication. Specific objectives were to quantify baseline adjective production, acquisition of target structures, and treatment generalisation effects.Method: A single-participant multiple-baseline design was used to evaluate treatment effects in three individuals with nonfluent chronic aphasia. A battery of experimental measures and standardised tests was also administered pre- and post-treatment to assess baseline performance and generalisation effects extending to adjectives, other parts of speech, sentence processing, and discourse production.Outcomes & Results: Two of the three participants acquired the target structures and maintained criterion performance levels 1 month after treatment. In spite of differences in baseline performance and responsiveness to treatment, all three participants demonstrated significant gains on standardised measures of language production.Conclusions: Findings add to existing literature supporting the viability of adjective training for individuals with aphasia. Participant characteristics and treatment factors that may contribute to variable outcomes are also discussed.

Estradiol and striatal dopamine receptor antagonism influence memory system bias in the female rat

Estradiol (E2) has been shown to influence learning and memory systems used by female rats to find a reward. Rats with high levels of E2 tend to use allocentric, or place, memory while rats with low levels of E2 use egocentric, or response, memory. It has been shown that systemic dopamine receptor antagonism interacts with E2 to affect which memory system is used. Here, dopamine antagonists were administered directly into either the dorsal striatum or nucleus accumbens to determine where in the brain this interaction takes place. Seventy-four young adult, female, Sprague-Dawley rats were trained and tested in a modified plus-maze. All rats were ovariectomized, received a subcutaneous low E2 implant, and were implanted with bilateral cannulae into either the dorsal striatum or the nucleus accumbens. Additionally, high E2 rats received daily injections of E2 in a sesame oil solution while low E2 rats received daily injections of vehicle. After reaching criterion levels of performance in a plus-maze task, rats were administered microinjections of either a dopamine D1 receptor (SCH 23390; 0.1μg/ml and 0.01μg/ml) or D2 receptor (raclopride; 2μg/ml and 0.5μg/ml) antagonist or a vehicle control (saline) in a counterbalanced manner. High E2 rats exhibited a trend towards a place memory bias while low E2 rats showed a response memory bias. Dorsal striatal administration of a D1, but not D2, dopamine receptor antagonist caused a switch in the memory system used by both high and low E rats. There was no significant effect of dopamine receptor antagonism in the nucleus accumbens group. Thus, E2 determined which memory system controlled behavior in a plus-maze task. Moreover, this effect was modulated by dopamine D1R antagonism in the dorsal but not ventral striatum suggesting that memory systems are, in part, mediated by E2 and dopamine in this region.

Influence of Hearing Loss on Children’s Identification of Spondee Words in a Speech-Shaped Noise or a Two-Talker Masker

This study evaluated the influence of hearing loss on children's speech-perception abilities in a speech-shaped noise or a two-talker masker. For both masker conditions, it was predicted that children with hearing loss would require a more advantageous signal to noise ratio (SNR) than children with normal hearing to achieve the same criterion level of performance. However, it was hypothesized that the performance gap between children with hearing loss and children with normal hearing would be larger in the two-talker than in the speech-shaped noise masker. A repeated-measures design compared the spondee identification performance of two age groups of children with hearing loss (9-11 and 13-17 years of age) and a group of children with normal hearing (9-11 years of age) in continuous speech-shaped noise or a two-talker masker. Estimates of the SNR required for 70.7% correct spondee identification were obtained using an adaptive, four-alternative, forced-choice procedure. Children were tested in the sound field. Children with hearing loss wore their personal hearing aids at their regular settings during testing. Both groups of children with hearing loss performed more poorly than children with normal hearing in the speech-shaped noise masker. Younger children required an additional 2.7 dB SNR and older children required an additional 4.7 dB SNR to achieve the same level of performance as children with normal hearing. This disadvantage decreased to 8.1 dB for both age groups of children with hearing loss in the two-talker masker. For children with hearing loss, degree of hearing loss was significantly correlated with performance in the speech-shaped noise masker, but not in the two-talker masker. A larger performance gap was observed between children with hearing loss and children with normal hearing in competing speech than in steady state noise. These results are consistent with the hypothesis that hearing loss influenced children's perceptual processing abilities.

Auditory scene analysis in budgerigars (Melopsittacus undulatus) and zebra finches (Taeniopygia guttata)

Deciphering the auditory scene is a problem faced by humans and animals alike. However, when faced with overlapping sounds from multiple locations, listeners are still able to attribute the individual sound objects to their individual sound-producing sources. Here, we determined which characteristics of sounds are important for streaming versus segregating in birds. Budgerigars and zebra finches were trained using operant conditioning procedures on an identification task to peck one key when they heard a whole zebra finch song and to peck another when they heard a zebra finch song missing a middle syllable. Once the birds were trained to a criterion performance level on those endpoint stimuli, probe trials were introduced on a small proportion of all trials. The probe songs contained modifications of the incomplete training song's missing syllable. When the bird responded as if the probe was a whole song, it suggests they streamed together the altered syllable and the rest of the song. When the bird responded non-whole song, it suggests they segregated the altered probe from the rest of the song. Results show that some features, such as spectrotemporal similarity and location, are more important for streaming than other features, such as timing.

Peer Assessment of Medical Lecturing: A Faculty Development Instrument

OPEN ACCESSMarch 11, 2013Peer Assessment of Medical Lecturing: A Faculty Development Instrument Lori R. Newman, MEd, Dara D. Brodsky, MD, David H. Roberts, MD, K. Meredith Atkins, MD, Richard M. Schwartzstein, MD Lori R. Newman, MEd Harvard Medical School Google Scholar More articles by this author , Dara D. Brodsky, MD Harvard Medical School Google Scholar More articles by this author , David H. Roberts, MD Harvard Medical School Google Scholar More articles by this author , K. Meredith Atkins, MD Harvard Medical School Google Scholar More articles by this author , Richard M. Schwartzstein, MD Harvard Medical School Google Scholar More articles by this author https://doi.org/10.15766/mep_2374-8265.9359 SectionsAboutAbstract ToolsDownload Citations ShareFacebookTwitterEmail AbstractAbstractPeer observation of teaching has become an important element in the assessment of faculty members' instructional skills and competence. Assessing teaching accurately involves the use of reliable and validated instruments, standardized observation procedures, and peer observer training. Without training, observers may provide biased feedback that lacks either sufficient detail or specific suggestions needed for teaching improvement. This resource contains an instrument for peer assessment of medical lecturing along with an accompanying rater training guide. The assessment instrument consists of 11 criteria for effective lecturing and an overall lecture quality measure. Together, the guide and instrument may be used for peer rater training as they provide faculty with detailed behavioral descriptors and guidance on conducting peer assessment of medical lecturing or large-group discussions. After the training, we asked participants to rate a posttest lecture using the instrument and the guide. To determine the effectiveness of the training, these posttest ratings were compared to ratings previously determined by a panel of expert medical educators who had watched the same videotaped lectures. Preliminary results comparing the experts' and participants' ratings indicated closer agreement on the posttest lecture. Moreover, the participants found the rater training facilitator's guide to be valuable in detailing exact behaviors associated with each criterion's performance levels, and they asked to keep the guide for future reference. Educational Objectives By using this resource, faculty should be able to: Encourage peer observation of teaching among faculty members resulting in specific, behavioral feedback and valuable discussions on best teaching practices.Provide faculty observers with detailed guidance on how to conduct peer observation using a standardized, reliable approach. Sign up for the latest publications from MedEdPORTAL Add your email below FILES INCLUDEDReferencesRelatedDetails FILES INCLUDED Included in this publication: Facilitator's Guide for Rater Training.pdf Instructor's Guide.pdf Peer Assessment Instrument.pdf To view all publication components, extract (i.e., unzip) them from the downloaded .zip file. Download editor’s noteThis publication may contain technology or a display format that is no longer in use. Copyright & Permissions© 2013 Newman et al. This is an open-access publication distributed under the terms of the Creative Commons Attribution-NonCommercial-Share Alike license.KeywordsLecturesPeer ObservationLarge Group DiscussionLecturingPeer EvaluationsPeer ReviewPeer Rater Training Disclosures None to report. Funding/Support None to report. Loading ...

Differential role of the dorsal hippocampus, ventro‐intermediate hippocampus, and medial prefrontal cortex in updating the value of a spatial goal

Encoding of a goal with a specific value while performing a place navigation task involves the medial prefrontal cortex (mPFC) and the dorsal hippocampus (dHPC), and depends on the coordination between mPFC and the ventro-intermediate hippocampus (vHPC).The present work investigates the contribution of mPFC, dHPC, and vHPC when the rat has to update the value of a goal. Rats were trained to navigate to an uncued goal in order to release a food pellet in a continuous place navigation task. When they had reached criterion performance level in the task, they were subjected to a single "flash session" in which they were exposed to an aversive strobe light during goal visits instead of receiving a food reward. Just before the flash session, the GABA(A) agonist muscimol was injected to temporarily inactivate mPFC, dHPC, or vHPC. The ability to recall the changed value of the goal was tested on the next day. We first demonstrate the aversive effect of the strobe light by showing that rats learn to avoid the goal much more rapidly in the flash session than during a simple extinction session in which goal visits are not rewarded. Furthermore, while dHPC inactivation had no effect on learning and recalling the new goal value, vHPC muscimol injections considerably delayed goal value updating during the flash session, which resulted in a slight deficit during recall. In contrast, mPFC muscimol injections induced faster goal value updating but the rats were markedly impaired on recalling the new goal value on the next day. These results suggest that, contrary to mPFC and dHPC, vHPC is required for updating the value of a goal. In contrast, mPFC is necessary for long-term retention of this updating.

Electrophysiological evidence for the action of a center-surround mechanism on semantic processing in the left hemisphere.

Physiological evidence was sought for a center-surround attentional mechanism (CSM), which has been proposed to assist in the retrieval of weakly activated items from semantic memory. The CSM operates by facilitating strongly related items in the “center” of the weakly activated area of semantic memory, and inhibiting less strongly related items in its “surround”. In this study weak activation was created by having subjects acquire the meanings of new words to a recall criterion of only 50%. Subjects who attained this approximate criterion level of performance were subsequently included in a semantic priming task, during which ERPs were recorded. Primes were newly learned rare words, and targets were either synonyms, non-synonymously related words, or unrelated words. All stimuli were presented to the RVF/LH (right visual field/left hemisphere) or the LVF/RH (left visual field/right hemisphere). Under RVF/LH stimulation the newly learned word primes produced facilitation on N400 for synonym targets, and inhibition for related targets. No differences were observed under LVF/RH stimulation. The LH thus, supports a CSM, whereby a synonym in the “center” of attention, focused on the newly learned word, is facilitated, whereas a related word in the “surround” is inhibited. The data are consistent with the view of this laboratory that semantic memory is subserved by a spreading activation system in the LH. Also consistent with our view, there was no evidence of spreading activation in the RH. The findings are discussed in the context of additional recent theories of semantic memory. Finally, the adult right hemisphere may require more learning than the LH in order to demonstrate evidence of meaning acquisition.

Perseverative behavior in rats with methamphetamine-induced neurotoxicity

Methamphetamine induces monoamine depletions thought to contribute to cognitive and behavioral dysfunctions. Previously, we reported that methamphetamine-induced neurotoxicity is associated with impaired formation of stimulus–response associations. Additionally, subjective observations suggested that behavioral flexibility might be affected. Thus, the present study examined whether methamphetamine neurotoxicity induces perseverative behavior. Rats were pretreated with (±)-methamphetamine (4 × 10 mg/kg, 2-hr intervals) or saline. Three weeks later, rats were trained to press a lever on one side of an operant chamber and then retrieve the reinforcer from a magazine on the opposite side until they reached criterion (>50 reinforcers/30-min). After four consecutive sessions performing the task at criterion, rats were sacrificed and brains removed for monoamine determinations. Methamphetamine-pretreated rats had ∼50% loss of striatal dopamine and prefrontal serotonin. Methamphetamine- and saline-pretreated rats were not different in the number of sessions required to reach criterion or in the total numbers of lever presses and/or head entries made across the four consecutive sessions at criterion-level performance. However, methamphetamine-pretreated rats earned fewer reinforcers, because they made extra lever-presses and head entries when they should have been retrieving the reinforcer or returning to the lever. Latencies for methamphetamine-pretreated rats to switch between the two behaviors also were significantly slower than latencies for controls. Interestingly, the degree of additional lever-presses negatively correlated with serotonin-transporter binding in the prefrontal cortex, even in saline-pretreated controls. These data suggest that methamphetamine-induced partial monoamine toxicity is associated with perseveration and that the degree of perseveration may depend on serotonin innervation of the frontal cortex.

Criterion-Based (Proficiency) Training to Improve Surgical Performance

OBJECTIVE To investigate whether training otorhinolaryngology residents to criterion performance levels (proficiency) on the Endoscopic Sinus Surgery Simulator produces individuals whose performance in the operating room is at least equal to those who are trained by performing a fixed number of surgical procedures. DESIGN Prospective cohort. SETTING Two academic medical centers in New York City. PARTICIPANTS Otorhinolaryngology junior residents composed of 8 experimental subjects and 6 control subjects and 6 attending surgeons. INTERVENTION Experimental subjects achieved benchmark proficiency criteria on the Endoscopic Sinus Surgery Simulator; control subjects repeated the surgical procedure twice. MAIN OUTCOME MEASURES Residents completed validated objective tests to assess baseline abilities. All subjects were videotaped performing an initial standardized surgical procedure. Residents were videotaped performing a final surgery. Videotapes were assessed for metrics by an expert panel. RESULTS Attendings outperformed the residents in most parameters on the initial procedure. Experimental and attending groups outperformed controls in some parameters on the final procedure. There was no difference between resident groups in initial performance, but the experimental subjects outperformed the control subjects in navigation in the final procedure. Most important, there was no difference in final performance between subgroups of the experimental group on the basis of the number of trials needed to attain proficiency. CONCLUSIONS Simulator training can improve resident technical skills so that each individual attains a proficiency level, despite the existence of an intrinsic range of abilities. This proficiency level translates to at least equal, if not superior, operative performance compared with that of current conventional training with finite repetition of live surgical procedures.

A Comparison Between Tact and Intraverbal Training in the Acquisition of a Foreign Language

The effects of tact versus intraverbal training were compared in terms of the transfer of stimulus control between verbal operants in the acquisition of a foreign language. The participants received training on tacts and two types of intraverbals with different stimulus sets. All types of training generated increases in correct responding on tests for emergent relations but tact training was the most efficient teaching procedure, because it required less training sessions and emergent responses reached criterion-level performance on all untrained operants.

Aging and Visual Counting

BackgroundMuch previous work on how normal aging affects visual enumeration has been focused on the response time required to enumerate, with unlimited stimulus duration. There is a fundamental question, not yet addressed, of how many visual items the aging visual system can enumerate in a “single glance”, without the confounding influence of eye movements.Methodology/Principal FindingsWe recruited 104 observers with normal vision across the age span (age 21–85). They were briefly (200 ms) presented with a number of well- separated black dots against a gray background on a monitor screen, and were asked to judge the number of dots. By limiting the stimulus presentation time, we can determine the maximum number of visual items an observer can correctly enumerate at a criterion level of performance (counting threshold, defined as the number of visual items at which ≈63% correct rate on a psychometric curve), without confounding by eye movements. Our findings reveal a 30% decrease in the mean counting threshold of the oldest group (age 61–85: ∼5 dots) when compared with the youngest groups (age 21–40: 7 dots). Surprisingly, despite decreased counting threshold, on average counting accuracy function (defined as the mean number of dots reported for each number tested) is largely unaffected by age, reflecting that the threshold loss can be primarily attributed to increased random errors. We further expanded this interesting finding to show that both young and old adults tend to over-count small numbers, but older observers over-count more.Conclusion/SignificanceHere we show that age reduces the ability to correctly enumerate in a glance, but the accuracy (veridicality), on average, remains unchanged with advancing age. Control experiments indicate that the degraded performance cannot be explained by optical, retinal or other perceptual factors, but is cortical in origin.

Playing action video games leads to better perceptual templates

Action video game playing substantially improves visual performance; however, the source of this improvement remains unclear. Here we use the equivalent external noise technique to characterize the mechanism(s) by which action video games may facilitate performance (Lu & Dosher, 1998). In a first study, Action Video Game Players (VGPs) and Non-Action Video Game Players (NVGPs) performed a foveal orientation identification task at different external noise levels. Threshold versus external noise contrast (TvC) functions were measured at two performance criterion levels. VGPs showed lower thresholds than NVGPs with a marked difference at high noise levels. Fitting the data with the Perceptual Template Model indicated that two independent factors contribute to the superior performance of VGPs: an 11% additive noise reduction and a 25% external noise exclusion. The causal effect of action video game playing was confirmed in a 50 hour training study, whereby NVGPs were randomly divided into an experimental group that played action video games and a control group that played control games. TvC functions were measured before and after training. The same change as in VGPs was observed in action game trainees, whereas no change in external noise reduction was observed in the control group. This work establishes that playing action video games leads to robust external noise exclusion, consistent with the use of better matched perceptual templates. To confirm that action video game playing leads to the development of better templates for the task at hand, we also used a probabilistic neural model of orientation selectivity. We found that changes in TvC curves induced by action video game playing can be captured by changing one parameter - the strength of the feedforward connections in the model. Together, this work demonstrates that action video game playing improves performance by allowing gamers to develop better task-relevant templates than non gamers.

Prototypical category learning in high‐functioning autism

An ongoing debate in developmental cognitive neuroscience is whether individuals with autism are able to learn prototypical category representations from multiple exemplars. Prototype learning and memory were examined in a group of high-functioning autistic boys and young men, using a classic paradigm in which participants learned to classify novel dot patterns into one of two categories. Participants were trained on distorted versions of category prototypes until they reached a criterion level of performance. During transfer testing, participants were shown the training items together with three novel stimulus sets manifesting variable levels of physical distortion (low, medium, or high distortion) relative to the unseen prototypes. Two experiments were conducted, differing only in the manner in which the physical distortions were defined. In the first experiment, a subset of autistic individuals learned categories more slowly than controls, accompanied by an overall diminution in transfer-testing performance. The autism group did, however, manifest a typical pattern of performance across the testing conditions, relative to controls. In the second experiment, group means did not differ statistically in either the training or testing phases. Taken together, these data indicate that high-functioning autistic individuals do not manifest gross deficits in prototypical category learning. A theoretical discussion is given in terms of how perceptual grouping may interact with category learning.

Global visual processing in macaques studied using Kanizsa illusory shapes

The ability to extract form information from a visual scene, for object recognition or figure-ground segregation, is a fundamental visual system function. Many studies of nonhuman primates have addressed the neural mechanisms involved in global form processing, but few have sought to demonstrate this ability behaviorally. In this study, we probed global visual processing in macaque monkeys (Macaca nemestrina) using classical Kanizsa illusory shapes as an assay of global form perception. We trained three monkeys on a "similarity match-to-sample" form discrimination task, first with complete forms embedded in fields of noncontour-inducing "pacman" elements. We then tested them with classic Kanizsa illusory shapes embedded in fields of randomly oriented elements. Two of the three subjects reached our criterion performance level of 80% correct or better on four of five illusory test conditions, demonstrating clear evidence of Kanizsa illusory form perception; the third subject mastered three of five conditions. Performance limits for illusory form discrimination were obtained by manipulating support ratio and by measuring threshold for discriminating "fat" and "thin" illusory squares. Our results indicate that macaque monkeys are capable of global form processing similarly to humans and that the perceptual mechanisms for "filling-in" contour gaps exist in macaques as they do in humans.

A comparison of four strategies for teaching a small foreign-language vocabulary.

We compared the effects of tact training, listener training, and two types of intraverbal training on 2 children's acquisition of foreign-language tact, listener, and intraverbal relations. The children received all four types of training simultaneously with different stimulus sets. Native-foreign intraverbal training presented the greatest difficulty with acquisition for both children. All types of training generated increases in correct responding on tests for emergent relations, and some emerged to criterion. However, no type of training resulted in criterion-level performance on all relations.