Effects of discriminability, probability of reinforcement, and handling cost on visual search and prey choice

Pigeons searched for two targets that varied in similarity to items in the background. The targets, simulating “prey,” were small alphabetic characters presented on computer monitors among distractor characters. In the first experiment, the probability of reinforcement for pecking at the targets was manipulated. In the second experiment, the response requirement for one of the targets was varied. Changing the probability of reinforcement led to more efficient search and increased choice for the more reinforced item. This effect carried over to subsequent equal reinforcement baseline conditions. Increasing the response requirement for one item increased response time for that item and reduced choice of the item. This effect did not carry over to a subsequent baseline condition. The results suggested that a high probability of reinforcement resulted in improved detection of the item, perhaps through perceptual learning, and increased the incentive that motivated response to the item, but that high response requirement resulted only in an incentive shift.     

Sequential priming in visual search: Contributions of stimulus-driven facilitation and learned expectancies

Sequential priming refers to speeded visual search when target identity or location is repeated within a trial sequence. In two experiments with pigeons, we addressed the relative contributions of stimulus-driven factors and learned expectancies to this effect. Pigeons pecked at targets during trialwise presentations of visual-search displays. Random-sequence conditions minimized the role of expectancy by introducing same-target or same-location trial sequences unpredictably. Blocked-sequence conditions added predictability by regular repetition of target and/or location over trials. Intertrial interval varied from 0.5 to 3 sec. The findings revealed significant reductions in reaction time during predictable target or location sequences compared with unpredictable repetitions within random contexts. Stimulus-driven factors do not seem to have an important role in many instances of sequential priming. Expectancy-based priming of target and location followed similar patterns.     

Markov choice processes in simultaneous matching-to-sample at different levels of discriminability

Decision and choice processes by pigeons were studied in a simultaneous matching-to-sample task. In order to view the recessed stimuli, the pigeons had to move in front of the pecking keys. They frequently moved back and forth between the comparison stimuli before choosing one of them as the match to the sample stimulus. These looking and choice responses were studied and recorded for five different discriminability levels, from near perfect (92%) to near chance (56%) performance, by changing the wavelength difference of the stimuli to be discriminated. The decision process was shown to be Markovian throughout the discriminability range, and the decision strategy based upon a Markov process is contrasted with other potential decision strategies.     

Searching image in blue jays: Facilitation and interference in sequential priming

Repeated exposure to a single target type (sequential priming) during visual search for multiple cryptic targets commonly improves performance on subsequent presentations of that target. It appears to be an attentional phenomenon, a component of the searching image effect. It has been argued, however, that if searching image is an attentional process, sequential priming should also interfere with performance on subsequent nonprimed targets, and such interference has never been unequivocally demonstrated. In blue jays (Cyanocitta cristata) searching in an operant apparatus for targets derived from images of cryptic moths, detection performance was strongly facilitated in the course of a sequential prime but was relatively unaffected by sequences of mixed target types. Detection accuracy in subsequent probe trials was enhanced by priming with targets of the same type, whereas accuracy on cryptic probes following priming with a more conspicuous target was significantly degraded. The results support an attentional interpretation of searching image.     

Gradient form and sequential effects during generalization testing in extinction

Four naive pigeons were given six generalization tests in extinction after periods of pretraining in which S+ appeared with food reinforcement and S? appeared in extinction. An analysis of sequential effects among presentations of test stimuli showed that the overall gradient was influenced differently by stimuli at the extremes of the continuum of test stimuli and by S+ and adjacent stimuli. Gradients consisting of responding in each stimulus when it was preceded by an extreme stimulus tended to peak at S+, while gradients produced when each stimulus was preceded by S+ or an adjacent stimulus tended to show a peak shift. This was true whether the overall gradient showed a peak shift or not. Two naive subjects were added and four additional tests were given after pretraining in which unequal frequencies of reinforcement accompanied both S+ and S?. Results of all 10 tests show that sequential effects occur during generalization testing in extinction and that these “local dimensional effects” are unlike local contrast. These stimulus-specific sequential effects may greatly influence overall gradient form.     

Priming during multiple-target search: The cumulative effects of relative target frequency

During search for multiple targets, reaction time decreases when a given target assumes a relatively high probability of appearance. Three experiments addressed the basis of this frequent-target effect. In a trialwise visual search method, pigeons pecked at the single target symbol embedded in a multisymbol display. In Experiment 1, the course of reaction times to frequent and infrequent targets was followed over extended sessions; reaction time to the frequent target dropped gradually over the first 200–400 trials. In Experiment 2, extinction sessions were introduced; the frequent-target effect persisted in the absence of reinforcement. In Experiment 3, the role of local trial patterns was examined; the frequent-target effect resisted temporary variations in relative target probability. Facilitation of search for high-probability targets appears to be an attentional rather than a conditioning effect; in the present design, information summarized over large sequences of trials appeared to provide pretrial information that primed attention.     

Adult word recognition and visual sequential memory

Two experiments were conducted investigating the role of visual sequential memory skill in the word recognition efficiency of undergraduate university students. Word recognition was assessed in a lexical decision task using regularly and strangely spelt words, and nonwords that were either standard orthographically legal strings or items made from words with internal transposed letters. Symbol memory was evaluated in a recognition procedure in which sequences of three to five unfamiliar complex symbols were presented, each followed by a subsequent array containing the symbols either in the same order or with an order transposition. In Experiment 1, there was no independent contribution of symbol memory to either word or nonword processing independently of the ability to discriminate the symbols from one another. In Experiment 2, although symbol memory made a significant contribution to word recognition independently of symbol discrimination and letter identification for two conditions??long strangely spelt words and short transposed-letter items, the effects were extremely small. It was concluded that non-verbal visual sequential memory skill does not play a central role in underpinning efficiency of word recognition in experienced adult readers.     

Shape recognition in infancy: visual integration of sequential information

To investigate the integration of visual information across space and time, infants watched the contour of a shape being traced out by a moving point source of light and then viewed 2 objects: 1 with the shape they had just seen traced and 1 with a novel shape. In the first study, which varied the number of tracings (velocity about 16.7 cm/sec), 12-month-olds looked longer at the novel object in all conditions, indicating that they recognized the similarity between the alternative object and tracing of like contour. Study 2, which varied velocity (14.7 and 7.4 cm/sec), stimuli, and the number of tracings, provided evidence for the generalizability of these results but indicated that performance suffered at the slower speed. Studies 3 and 4 held velocity constant (14.7 cm/sec) while varying the size of the tracings and age of the infant: 12-month-olds, but not 6-month-olds, recognized figures in instances where it took up to 10 sec to complete a single tracing. Because it took so long to complete many of the tracings, central rather than purely retinal mechanisms appear to be involved in integrating shape in these situations.     

Coloured overlays,visual discomfort,visual search and classroom reading

Forty-six children aged 12–16 were shown a page of meaningless text covered in random order by different plastic overlays, including seven that were various colours and one that was clear. By successive pairwise comparison each child selected the overlay that provided the greatest perceptual clarity of the text. The children with below-average reading ability were more likely to chose a coloured overlay, and they reported more perceptual difficulty on tasks devised by Irlen (1983). In separate sessions with and without the overlay of their choice, the children read for 15 minutes and performed a visual search task. The overlay had little effect on reading initially, but after about 10 minutes the children who chose a coloured overlay read more slowly without the overlay than with it. These children reported more symptoms of visual discomfort and showed signs of tiring when they read without the overlay. The visual search performance of the children who chose a coloured overlay was initially impaired but improved to normal levels when the overlay was used. Fourteen children aged 8–16 acted as chronological or reading age-matched controls, and undertook the reading and visual search tasks using a clear overlay which had no effect on performance.     

Automatic activation of phonological code during visual word recognition in children: a masked priming study in grades 3 and 5

The present study aimed to investigate the development of automatic phonological processes involved in visual word recognition during reading acquisition in French. A visual masked priming lexical decision experiment was carried out with third, fifth graders and adult skilled readers. Three different types of partial overlap between the prime and the target were contrasted: orthographic and phonological overlap (O+P+; ren-RENDRE [give] pronounced /?ɑ?/-/?ɑ?d?/ respectively), orthographic overlap (O+P?; re-RENDRE pronounced /??/-/?ɑ?d?/ respectively), or without orthographic and phonological overlap with the beginning of the target, namely unrelated (UR; pi-RENDRE pronounced /pi/-/?ɑ?d?/, respectively). The number of letters was controlled throughout the priming conditions. The results showed an interaction between grade and priming condition in children. In third graders, the results displayed a masked phonological priming effect (the O+P+ condition was compared to the O+P? condition) but not a masked orthographic priming effect (the O+P? condition was compared to the UR condition). On the contrary, in fifth graders, the results showed a masked orthographic priming effect but not a masked phonological priming effect. Adult skilled readers displayed the same pattern as fifth graders. These results are interpreted in the multiple-route model of reading development.     

Orthographic analogies and phonological priming effects

Bowey, Vaughan and Hansen (1998) have demonstrated that once phonological priming effects have been taken in account, there is no orthographic analogy effect for words with common end patterns (e.g. beak–peak). Goswami (1999) has argued that the study on which this claim is based is methodically flawed. This paper attempted to verify Bowey et al.’s claim by using an improved clue‐word procedure with a group of beginning readers, whose phonological awareness and vocabulary was also assessed. The results indicated that while rime‐based analogies seem to be phonological rather than orthographic in nature, beginning readers are able to use an orthographic analogy strategy when reading words that have similar beginnings (e.g. beak–bean).     

School choice and the search for an educational market

This article looks at attempts to create markets in schooling by increasing school choice, making particular reference to a study by the Organisation for Economic Cooperation and Development (OECD) of the impact of choice policies in six countries: Australia, England, the Netherlands, New Zealand, Sweden and the United States. The main policies examined are subsidies to private schools and enhancement of choice between schools within the public sector. The article identifies five kinds of imperfection in school markets in practice: the failure of clear alternatives to present themselves to consumers; the arbitrariness of criteria for choosing; limits to capacity at popular schools; the failure of supply to diversify in response to consumer pressures and the existence of negative externalities. It is argued that these imperfections make it necessary to intervene to maximise the benefits and minimise the risks of school choice.

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Zusammenfassung Unter Bezugnahme auf eine Studie der OECD (Organisation for Economic Cooperation and Development — Organisation für wirtschaftliche Zusammenarbeit und Entwicklung) beschreibt dieser Artikel Versuche, Märkte im Schulwesen durch erhöhte Schulauswahl zu schaffen. Die OECD-Studie beinhaltet die Auswirkungen der Auswahlpolitik in sechs Ländern: Australien, England, die Niederlande, Neuseeland, Schweden und die Vereinigten Staaten. Zu den wesentlichen hier untersuchten politischen Maßnahmen gehören Zuschüsse für private Schulen und die Förderung der Wahlmöglichkeiten bei öffentlichen Schulen. Der Artikel verweist auf fünf Mängel des Schulmarktes: fehlende klare Alterntiven für den Verbraucher, Willkür der Auswahlkriterien, Grenzen der Kapazitäten an populären Schulen, fehlende Diversifizierung als Antwort auf den Druck durch den Verbraucher und das Bestehen negativer äußerer Umstände. Der Autor argumentiert, daß diese Mängel ein gewisses Maß an Intervention benötigen, um Vorteile zu maximieren und die Risiken bei der Schulwahl so gering wie möglich zu halten.

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Résumé Cet article passe en revue les tentatives de création de marchés dans le domaine éducatif grâce à l'élargissement des possibilités de choix sur le plan de la scolarité. Il se fonde en particulier sur une étude menée par l'Organisation de Coopération et de Développement Economiques (OCDE) analysant l'impact des politiques de choix dans six pays: l'Australie, l'Angleterre, les Pays-Bas, la Nouvelle-Zélande, la Suède et les Etats-Unis. Les principales politiques examinées sont les suivantes: subventions accordées aux écoles privées et plus grand choix entre les différentes écoles du secteur public. L'article révèle que, dans la pratique, les marchés scolaires présentent cinq imperfections: le manque d'alternatives clairement identifiables par le consommateur; le caractère arbitraire des critères de choix; les capacités limitées des écoles les plus désirées; l'absence d'une diversification répondant à la demande des consommateurs et l'existence de facteurs externes négatifs. Ces imperfections nécessiteraient une intervention pour optimiser les bénéfices et minimaliser les risques liés au choix scolaire.

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Sumario El artículo enfoca los intentos realizados para crear mercados en la educación mediante la elección de escuela y hace especial referencia a un estudio de la OCDE sobre el impacto de las políticas de elección en seis países: Australia, Inglaterra, Holanda, Nueva Zelandia, Suecia y los Estados Unidos. Las principales actividades examinadas son los subsidios a las escuelas privadas y el perfeccionamiento de la elección de escuela en el sector público. En el artículo se señalan cinco tipos de defectos presentes en la práctica: la carencia de diversidad en las ofertas presentadas a los consumidores, la arbitrariedad de los criterios de election, los límites de capacidad en escuelas popularies, la falta de respuestas a los deseos de los consumidores y la existencia de factores externos negativos. Aquí se aboga por una intervención, para maximizar los beneficios y minimizar los riesgos de la elección de escuela.

     

Phonological contribution during visual word recognition in child readers. An intermodal priming study in Grades 3 and 5

This study investigated the phonological contribution during visual word recognition in child readers as a function of general reading expertise (third and fifth grades) and specific word exposure (frequent and less‐frequent words). An intermodal priming in lexical decision task was performed. Auditory primes (identical and unrelated) were used in order to directly activate phonological codes independently of orthographic processing. Overall, the results revealed a widespread phonological priming effect in both grades. There was a significant interaction between grade, priming condition and frequency, revealing that the impact of frequency on identity priming differed between grades. In third grade, the results indicated that the priming effect was greater for less‐frequent than for frequent words. In fifth grade, priming effects were similar for both frequent and less‐frequent words. These findings indicate that print and speech processing systems are interconnected in young readers. Moreover, phonological codes play an important role in word recognition throughout reading development.     

Lexical-semantic processing and reading: relations between semantic priming,visual word recognition and reading comprehension

The aim of this study was to investigate relations between lexical-semantic processing and two components of reading: visual word recognition and reading comprehension. Sixty-eight children from private schools in Porto Alegre, Brazil, from 7 to 12 years, were evaluated. Reading was assessed with a word/nonword reading task and a reading comprehension task. Lexical-semantic processing was evaluated with a semantic priming experiment. Correlations were conducted in order to examine the relations between semantic priming effects (SPEs) and performance in reading tasks. Regression analyses were performed to test the hypothesis that word reading mediates the relation between semantic priming and reading comprehension. The results showed that SPEs correlated with both word reading and reading comprehension measures. Additionally, partial mediation by word reading was found for the prediction of reading comprehension by SPEs. The results are discussed in the context of reading models and other studies relating semantic priming and reading measures.     

Orthographic processing and visual sequential memory in unexpectedly poor spellers

Does unexpectedly poor spelling in adults result from inferior visual sequential memory? In one experiment, unexpectedly poor spellers performed significantly worse than better spellers in the immediate reproduction of sequences of visual symbols, but in a second experiment, the effect was not replicated. Poor spellers were also no worse at the immediate recognition of symbol sequences. Overall, the results indicate that inferior visual memory is not characteristic of unexpectedly poor spellers. However, they do have less efficient orthographic processing skill: they were significantly slower and more error prone than better spellers at classifying both regularly and strangely spelt words, as well as at detecting letter transpositions in long words. They can thus be considered as subtly worse word readers than better spellers. While the findings question the notion of unexpectedly poor spelling in relation to normal adults, they provide confirmation of the intimate relationship between reading and spelling processes.     

The effects of search tool type and cognitive style on performance during hypermedia database searches

This study investigated the effects of search tools and learner cognitive styles on performance in searches for information within a hypermedia database. Seventy-five students in a university English as a Second Language (ESL) program were blocked for field dependence and assigned to one of four treatments: browser, index/find, map, and all tools. Subjects searched the hypermedia database, EarthQuest, for facts to answer practice and posttest questions on science topics. Results revealed a significant interaction between search tool and cognitive style. Field-independent learners performed significantly better than field-dependent learners under the index/find and map treatments. Subjects in the four treatment groups accessed information from the database differently. Furthermore, cognitive style was significantly related to achievement, tool use, and attitude. Implications for the design and instructional use of hypermedia databases are provided.     

Memory priming and trial spacing effects in Pavlovian learning

Conditioning trials that are massed in time produce less conditioning than those that are spaced in time. Four experiments with rat subjects examined whether a recent conditioning trial interferes with conditioning on the next trial by temporarily “priming” information in short-term memory (e.g., Wagner, 1978, 1981). We used appetitive conditioning procedures in which priming trials preceded target trials by 60 sec. When the priming trials were nonreinforced presentations of a conditioned stimulus (CS), the CS had to be the same CS as the one on the target trial to interfere with conditioning. When priming trials were actual CS-unconditioned stimulus (US) pairings, the CS identity did not matter; the US was the event that interfered with conditioning on the next trial. Reinforced trials reduced performance in a way that did not depend on context blocking. The results suggest that CS and US priming effects do contribute to conditioning deficits observed with massed trial procedures. The results are consistent with Wagner’s (1981) “sometimes opponent process,” or SOP, model, although a result that is paradoxical for the model suggests that recent USs may have motivational as well as memory effects.