Types Of Discrimination Tasks Research Articles

Does the type of task affect prey discrimination learning in avian predators?

AbstractWhen learning to discriminate between palatable and unpalatable prey, predators may encounter the prey either simultaneously or in a sequence. The two types of discrimination tasks, which are frequently used in experiments focused on aposematism and mimicry, may considerably differ in difficulty, as they differ in the information available to predators during individual encounters with prey. Surprisingly, there are very few studies directly comparing the performance of predators between sequential and simultaneous discrimination tasks using otherwise identical experimental design, the same predators and prey. We tested the effect of the type of discrimination task on the effectiveness of discrimination learning in adult and juvenile great tits (Parus major). Birds were trained to discriminate between palatable and unpalatable artificial prey items baited with mealworms soaked either in water or quinine. Prey shape, colours and patterns were derived from real shield bug species. We compared the performance of birds tested with two discriminative cues, colour and pattern, using three discrimination tasks: (1) sequential—alternating presentation of one palatable and one unpalatable prey item, (2) two‐choice—simultaneous presentation of one palatable and one unpalatable prey item and (3) multiple‐choice—simultaneous presentation of multiple palatable and unpalatable prey items. Colour was a more effective discriminative cue than pattern for both adult and juvenile birds. Adults performed better than juveniles regardless of task. The birds performed equally well in the sequential and two‐choice tasks, but their performance in the multiple‐choice task was worse than in the other two tasks. However, these differences were only present when the birds used the pattern as a discriminative cue. The birds tested with colour, a more salient cue, performed equally well in all three tasks. Type of discrimination task may therefore affect the learning performance of predators, but the effect also depends on the saliency of a particular discriminative cue.

Pigeons use high spatial frequencies when memorizing pictures.

The ability of animals to visually memorize and categorize a large number of pictures is well established. Determining the kinds of information animals use to accomplish these goals has been more difficult. This experiment examined the contribution of spatial frequency information to picture memorization by pigeons. A series of grayscale pictures were notch-filtered to eliminate different portions of the spatial frequency spectrum of memorized pictures. The results indicated that the higher spatial frequencies in the pictures were most important to accurate recognition, suggesting that the detection of fine detail at the high range of pigeon visual acuity was a critical component to their memorized representations. Subsequent tests with band-pass and hybrid conflict stimuli confirmed this conclusion. It is suggested that cognitive and task demands may determine how spatial frequency is used by pigeons, with higher frequencies more important to item memorization, while lower spatial frequencies may contribute to categorization in other types of discrimination tasks.

Visually guided decision making in foraging honeybees.

Honeybees can easily be trained to perform different types of discrimination tasks under controlled laboratory conditions. This review describes a range of experiments carried out with free-flying forager honeybees under such conditions. The research done over the past 30 or so years suggests that cognitive abilities (learning and perception) in insects are more intricate and flexible than was originally imagined. It has become apparent that honeybees are capable of a variety of visually guided tasks, involving decision making under challenging situations: this includes simultaneously making use of different sensory modalities, such as vision and olfaction, and learning to use abstract concepts such as “sameness” and “difference.” Many studies have shown that decision making in foraging honeybees is highly flexible. The trained animals learn how to solve a task, and do so with a high accuracy, but when they are presented with a new variation of the task, they apply the learnt rules from the earlier setup to the new situation, and solve the new task as well. Honeybees therefore not only feature a rich behavioral repertoire to choose from, but also make decisions most apt to the current situation. The experiments in this review give an insight into the environmental cues and cognitive resources that are probably highly significant for a forager bee that must continually make decisions regarding patches of resources to be exploited.

Correlations between neuropsychological test results and P300 latency during silent-count and button-press tasks in post-traumatic brain injury patients

To evaluate the correlations between memory function and intelligence and event-related potential, the P300 component for different tasks was studied for 30 post-traumatic brain injury patients (mean age 31.6 ± 13.7 years; 23 male and 7 female). Memory function, intelligence, and depression were measured by using the Mini-Mental State Examination, the revised Wechsler Adult Intelligence Scale and the Self-Rating Depression Scale, respectively. P300 latency was measured during silent-count and button-press tests at three midline scalp (Fz, Cz, and Pz) sites for all subjects by using an auditory ‘odd-ball’ paradigm. Neuropsychological memory score was predicted by intelligence score, but neurophysiological P300 latency was predicted by memory score for the silent-count test and by intelligence score for the button-press test. These results show that the P300 event-related potential component is sensitive to the diverse nature of cognitive deficits in post-traumatic brain injury patients during different types of discrimination tasks. However, future research is necessary to replicate and extend these findings.

A model of auditory pattern analysis based on component-relative-entropy.

Recently results from detection and information theory have been used to predict performance of human observers in experiments involving the discriminability of changes in individual components of unfamiliar or uncertain tone patterns [R. A. Lutfi, J. Acoust. Soc. Am. 91, 3391-3401 (1992)]. In this paper, the theoretical analysis is expanded to yield a general rule of pattern analysis that accounts for nearly all of the major results of such experiments conducted over the last 18 years. The rule can be stated as follows: Component discriminability in an unfamiliar tone pattern (profile or sequence) is a linearly increasing function of the component's relative entropy (CoRE) in the pattern. Ancillary: The threshold for detection of a change decreases by one order of magnitude (factor of 10) for each one bit increase in CoRE. This precise relation of threshold to CoRE is demonstrated repeatedly in a review of past studies, and is shown to account for the relative effects of a variety of important variables and their interactions. Such variables include the total duration of the pattern; the number of tones in the pattern; the number of tones subject to change; the relative level and duration of individual tones in the pattern; the relative variability and the physical dimension of the tones' parameters that are subject to change; the number and position of targets in the pattern; the psychophysical procedure used (method of adjustment versus same-different), the type of discrimination task (frequency versus intensity discrimination), and the manner of presentation of the tones (simultaneous or sequential). The CoRE rule seems to reflect a general property of auditory analysis wherein the perception of patterns in an ensemble is dominated by those features that dominate the variance of the ensemble.

Differential effects of opioid and nonopioid analgesics on conditional discriminations in pigeons

Under the fixed-consecutive-number schedule (FCN), pigeons were reinforced for responding eight or more times on one response key (work key), and then responding once on a second response key. In one component of this schedule, an external stimulus signalled the completion of the response requirement on the work key (FCN 8-SD), whereas no stimulus change was programmed under the other (FCN 8). Across a range of doses, the mu opioid agonist morphine, the kappa opioid agonist U50,488 and the opioid antagonist naloxone had no consistent effect on accuracy under either FCN schedule. Naloxone and accuracy under either FCN schedule. Naloxone and U50,488 produced a general flattening of the conditional probability functions by decreasing the conditional probability of response runs exceeding the minimum response requirement of eight consecutive responses on the work key. The sigma agonists phencyclidine and (+)N-allylnormetazocine and the nonopioid analgesics clonidine and l-nantradol produced large decreases in accuracy under the FCN 8 and small decreases under the FCN 8-SD. With the exception of (+)N-allylnormetazocine, these drugs consistently increased the conditional probability of responses runs shorter than the minimum response requirement on the work key. These findings indicate that the accuracy-altering effects of some opioid and nonopioid analgesics depend in part on the type of discrimination task.

Relationship between Auditory Discrimination, Articulation Stimulability, and Consistency of Misarticulation

A study was conducted to measure the relationship between auditory discrimination, articulation stimulability, and consistency of misarticulation. Data were based on the Carter-Buck Nonsense-Syllable Imitation Test for stimulability of /s/, the McDonald Deep Test of Articulation which measured consistency of misarticulation of /s/, and the Farquhar-Bankson In-depth Test of Auditory Discrimination which measured external and internal auditory discrimination of /s/. Ss were 25 kindergarten and first grade children with normal hearing and intelligence. No S had received any speech therapy. Each S misarticulated a minimum of three /s/ items on the McDonald Screening Test of Articulation. No more than one phoneme was misarticulated in addition to misarticulation of /s/. A significant correlation between the child's ability to discriminate his own production of /s/ (internal or self-monitoring) and the consistency of misarticulation of /s/ was obtained, as well as one between the consistency of misarticulation of /s/ and the stimulability of /s/. No statistically significant correlations were found between the other variables. A low nonsignificant correlation was found between the stimulability of /s/ and internal discrimination abilities. Different types of discrimination tasks were of varying difficulty. Performance on external discrimination items was better than for internal discrimination items.

Infant recognition memory: the effects of length of familiarization and type of discrimination task.

FAGAN, JOSEPH F., III. Infant Recognition Memory: The Effects of Length of Familiarization and Type of Discrimination Task. CmLD DEVELOPMENT, 1974, 45, 351-356. Infant recognition memory, defined by novelty preferences, was found to vary over 4 discrimination tasks as a function of length of familiarization for 5--6-month-old infants. Briefer amounts of familiarization were effective for eliciting recognition than had previously been demonstrated. Order of task difficulty corresponded to age-related differences in ease of discrimination.

Infant Recognition Memory: The Effects of Length of Familiarization and Type of Discrimination Task

Infant Recognition Memory: The Effects of Length of Familiarization and Type of Discrimination Task

Training procedures and task difficulty in brightness and position discriminations by rats.

This research concerned training procedures (correction vs noncorrection), type of discrimination task (position vs brightness), and task difficulty in two 2 × 3 experiments using rats in single-unit mazes. An interaction was found between type of training procedure and task difficulty for the brightness task, with noncorrection Ss requiring relatively fewer trials to reach a criterion than correction Ss as the task became more difficult. A statistically insignificant interaction was found for the position task.

Effects of body weight loss on position and brightness discrimination tasks

Thirty-six male, albino rats were given discrimination training in a T-maze. The design consisted of a 3 × 2 factorial combining three levels of drive (95%, 85%, and 75% mean ad lib body weight loss) and two types of discrimination tasks (position and brightness). It was found that discrimination learning was facilitated by increased drive and Ss that were reduced to 85% and 75% their mean ad lib body weights learned the position problem in less days and with fewer errors to criterion than animals trained on the brightness task. However, as a function of an initially strong tendency for rats trained under low drive to demonstrate spontaneous alternation behavior task differences, as measured by errors to criterion, were not found.

Verbal discrimination learning as a function of associative strength between the word-pair members

Derivations from associative generalization experiments and the frequency theory of verbal discrimination learning were tested in four experiments. Exps. I and IV used the usual simultaneous verbal discrimination procedure, Exp. II used a successive discrimination procedure, and Exp. III used a differential discrimination procedure. Exps. I-III were conducted with college S s and Exp. IV was conducted with fourth-grade children. In all four experiments discriminations were required between pairs of words of high, intermediate or zero free-association strength, and in all cases the difficulty of the discrimination was positively related to association strength although the overall difficulty of learning was related to the type of discrimination task employed. The results were interpreted as supporting the frequency theory of verbal discrimination learning.