Víctor Navarro

Víctor Navarro
Cardiff University | CU

PhD

About

19
Publications
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150
Citations

Publications

Publications (19)
Article
We explored the relation between concept learning and the number of training exemplars, programmed in a stepwise fashion. Eight pigeons (Columba livia) were trained via differential food reinforcement to peck 1 of 2 simultaneously displayed color images: benign or malignant human breast tissue samples. In each session, only 1 exemplar from each cat...
Article
Full-text available
Pathologists and radiologists spend years acquiring and refining their medically essential visual skills, so it is of considerable interest to understand how this process actually unfolds and what image features and properties are critical for accurate diagnostic performance. Key insights into human behavioral tasks can often be obtained by using a...
Article
Full-text available
How supervision is arranged can affect the way that humans learn concepts. Yet very little is known about the role that supervision plays in nonhuman concept learning. Prior research in pigeon concept learning has commonly used differential response–reinforcer procedures (involving high-level supervision) to support reliable discrimination and gene...
Article
Sleep supports the consolidation of memory, and it has been proposed that this enhancing effect of sleep pertains in particular to memories which are encoded under control of prefrontal-hippocampal circuitry into an episodic memory system. Furthermore, repeated reactivation and transformation of such memories during sleep are thought to promote the...
Article
Pigeons readily learn and transfer same-different discriminations in a variety of experimental paradigms. However, strategically designed probe tests suggest that they might only represent sameness. Here, we provide the first direct evidence that pigeons also represent difference. We first trained pigeons on a conditional same-different discriminat...
Article
Attention to relevant stimulus features in a categorization task helps to optimize performance. However, the relationship between attention and categorization is not fully understood. For example, even when human adults and young children exhibit comparable categorization behavior, adults tend to attend selectively during learning, whereas young ch...
Article
The study of bidirectional conditioning began more than a century ago, yet it has failed to take strong root in psychology and neuroscience. We revisit this topic by exploiting E. A. Asratyan’s alternating procedure of stimulus presentation, in which both forward (e.g., A→B) and backward (e.g., B→A) training trials are concurrently given, in order...
Article
In two experiments, we trained pigeons (Columba livia) to sort visual images (obtained by clinical myocardial perfusion imaging techniques) depicting different degrees of human cardiac disfunction (myocardial hypoperfusion of the left ventricle) into normal and abnormal categories by providing food reward only after correct choice responses. Pigeon...
Article
Two experiments analyzed the role of extinction cues (EC) and stimuli associated to them in the reacquisition of conditioned ethanol tolerance. Ethanol-induced ataxia was measured in 80 rat subjects using a tilting plane, in a 5-phase procedure. The first experiment (which used 4 contexts and 40 rats) showed that the presentation of the extinction...
Article
In a seminal study, Shepard, Hovland, and Jenkins (1961; henceforth SHJ) assessed potential mechanisms involved in categorization learning. To do so, they sequentially trained human participants with 6 different visual categorization tasks that varied in structural complexity. Humans' exceptionally strong performance on 1 of these tasks (Type 2, or...
Article
We trained 8 pigeons (Columba livia) on a stagewise go/no-go visual discrimination task of increasing complexity, to document the dynamics of selective attention. We constructed negative compound stimuli (S-s) on the basis of their overall similarity to a positive compound stimulus (S+) along 4 binary-valued dimensions: shape (circle/square), size...
Article
Considerable research in cognitive science, neuroscience, and developmental science has revealed that the temporal, spatial, and numerical features of a stimulus can interact with one another [1,2, as when larger stimuli are perceived as lasting longer than smaller stimuli. These findings have inspired the prominent hypothesis that time, space, and...
Conference Paper
Full-text available
We trained eight pigeons (Columba livia) on a stepwise go/no-go task of increasing complexity, in order to document the dynamics of discrimination learning involving complex visual stimuli. We constructed compound stimuli on the basis of their similarity to the S+, from 4 binary-valued dimensions: shape (circle/square), size (large/small), line ori...
Article
We report a novel method for investigating the acquisition of anticipatory responding in the pigeon. Four pigeons (Columba livia) received food for pecking a starburst target stimulus displayed in the bottom-left or bottom-right portion of a computer screen. The target stimulus was preceded by 1 of 3 fractal images displayed in either the upper-lef...
Article
Full-text available
Given the mixed results in literature and the lack of human studies, a fear conditioning paradigm was used to evaluate whether the use of massive or moderate extinction trials have a diff erential eff ect on the recovery of extinguished fear, when assessed outside of the extinction context (an abc renewal design), and after a delay (spontaneous rec...
Conference Paper
Full-text available
To document the dynamics of discrimination learning involving increasingly complex visual stimuli, we trained six pigeons in a stagewise Multiple Necessary Cues (MNC) go/no-go task. The compound stimuli were composed from 4 dimensions, each of which could assume either of two extreme values or the intermediate value between them. Starting with a st...
Article
Full-text available
We trained six pigeons in a stagewise Multiple Necessary Cues (MNC) go/no-go task to document the dynamics of discrimination learning involving increasingly complex visual stimuli. The compound stimuli were composed from four dimensions, each of which could assume either of two extreme values or their intermediate value: Shape, Size, Line Orientati...
Conference Paper
Assessment of medical image quality and how changes in image appearance impact performance are critical but assessment can be expensive and time-consuming. Could an animal (pigeon) observer with well-known visual skills and documented ability to distinguish complex visual stimuli serve as a surrogate for the human observer? Using sets of whole slid...

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