Rapid visual processing of picture stimuli by pigeons in an RSVP (rapid serial visual presentation) task.

Three experiments that were carried out in series with 5 pigeons used novel training methods to investigate the rapid visual processing of picture stimuli by pigeons. On each trial, a sequence containing 1 of 2 bird pictures (the target) and nontarget bird pictures (the distractors) was presented. After the termination of the last item in the sequence, the pigeons were required to choose 1 of 2 colored squares corresponding to the target presented in the preceding sequence.

Efficient visual search for multiple targets among categorical distractors: effects of distractor-distractor similarity across trials.

We trained one group of pigeons to search for members of an artificial category among category-unspecified nonmembers. For another group of pigeons, the roles of the targets and of the distractors were reversed. Experiment 1 found that the latter group showed surprisingly efficient search for multiple nonmembers.

Discrimination of coherent and incoherent motion by pigeons: an investigation using a same-different motion discrimination task.

We trained seven pigeons to discriminate arrays of 8 identical icons that made small random movements in the same direction (coherent movement) from arrays of 8 identical icons that made small random movements in different directions (incoherent movement), with each icon moving within its own cell in an invisible 4×4 grid. During initial training, one specific configuration of icons (a fixed array) was used. The pigeons learned this discrimination and were later trained with successively introduced novel fixed arrays, and finally with novel arrays of random spatial arrangements (random arrays).

Pigeons show efficient visual search by category: effects of typicality and practice.

Three experiments investigated category search in pigeons, using an artificial category created by morphing of human faces. Four pigeons were trained to search for category members among nonmembers, with each target item consisting of an item-specific component and a common component diagnostic of the category. Experiment 1 found that search was more efficient with homogeneous than heterogeneous distractors.

Flexible learning and use of multiple-landmark information by pigeons (Columba livia) in a touch screen-based goal searching task.

Three touch screen-based experiments were conducted to investigate whether pigeons would learn to use configural information about a goal's location in relation to a multiple-landmark array. In Experiment 1, 4 pigeons (Columba livia) were trained to peck a computer monitor at a location that constituted the third vertex of a hypothetical triangle defined by 2 different landmarks. The landmarks appeared in 3 orientations during the training, and the pigeons' goal-searching ability easily transferred to the landmarks presented in 3 novel orientations.

The learning of basic-level categories by pigeons: the prototype effect, attention, and effects of categorization.

Pigeons were trained to classify composite faces of two categories created by mimicking the structure of basic-level categories, with each face consisting of an item-specific component and a common component diagnostic for its category. Classification accuracy increased as the proportion of common components increased, regardless of familiar and novel item-specific components, with the best discrimination occurring at untrained original faces used as the common components. A no-categorization control condition suggested that categorization gives rise to equivalence for item-specific components and distinctiveness for degrees of prototypicality.

A slowing effect on visual search by advance information in pigeons (Columba livia): a comparison with humans (Homo sapiens).

A comparative study was conducted to investigate whether the search for a target letter was facilitated when the target and prime (preceding stimulus) letters were identical. Pigeons (Section 2) and human participants (Section 3) were first trained to search for "A" among "Y"s and "E" among "D"s in a condition in which a square shape appeared as the prime (Neutral condition). In subsequent testing, a prime was identical either to the corresponding target (Target-priming condition) or to the distractor (Distractor-priming condition).

Counting absolute numbers of items, from 1 to 8, in pigeons.

Pigeons were trained in a forced choice task with four alternatives to categorize arrays consisting of 1, 3, 5, or 8 dots. Before the pigeons chose a comparison stimulus, they were required to peck each dot sequentially. A single peck to a dot, which was defined as an indicating response, changed the color of the dot so that it was differentiated from those that remained to be counted.

Discrimination of artificial categories structured by family resemblances: a comparative study in people (Homo sapiens) and pigeons (Columba livia).

Adult humans (Homo sapiens) and pigeons (Columba livia) were trained to discriminate artificial categories that the authors created by mimicking 2 properties of natural categories. One was a family resemblance relationship: The highly variable exemplars, including those that did not have features in common, were structured by a similarity network with the features correlating to one another in each category. The other was a polymorphous rule: No single feature was essential for distinguishing the categories, and all the features overlapped between the categories.

Family resemblances facilitate formation and expansion of functional equivalence classes in pigeons.

Four pigeons were given repeated reversal training and testing with photographs of human faces constituting two categories structured by family resemblances, each consisting of a prototype, good exemplars, and poor exemplars. Each of the good exemplars (AM, BM, and CM) was created by 50% morphing of the prototype (M) and one of the poor exemplars (A, B, and C, respectively) and thus was physically similar to the prototype and to the corresponding poor exemplar. The pigeons were first trained and tested for the formation of two (AM, BM, and CM) classes.

Recognition of static and dynamic images of depth-rotated human faces by pigeons.

In three experiments, we examined pigeons' recognition of video images of human faces. In Experiment 1, pigeons were trained to discriminate between frontal views of human faces in a go/no-go discrimination procedure. They then showed substantial generalization to novel views, even though human faces change radically as viewpoint changes.

Pigeon's recognition of cartoons: effects of fragmentation, scrambling, and deletion of elements.

J. Cerella [Pattern Recognit. 12 (1980) 1] and more recently S.

A new approach to the formation of equivalence classes in pigeons.

Four pigeons were given simultaneous discrimination training with visual patterns arbitrarily divided into two sets, with the stimuli in one set designated A1, B1, C1, and D1 and those in the other set designated A2, B2, C2, and D2. In sequentially introduced training phases, the pigeons were exposed to a series of reversals to establish AB and then CD equivalences. In subsequent testing sessions, a subset of stimuli from one set served as positive stimuli and those from the other set as negative stimuli on training trials, and transfer of the reinforced relation to other members of the sets was tested with nonreinforced probe trials.