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1.
Int J Parasitol Parasites Wildl ; 21: 264-268, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37520899

ABSTRACT

In Japan, the recent series of sporadic outbreaks of human trichinellosis caused by Trichinella (Nematoda: Trichocephalida) has occurred owing to the consumption of raw or insufficiently cooked meat from wild bears. However, the infection status and molecular characteristics of Trichinella larvae in Japanese wild bears remain poorly understood. This study investigated the prevalence of Trichinella spp. in brown bears (Ursus arctos) from Hokkaido, and Japanese black bears (Ursus thibetanus japonicus) from three prefectures (Aomori, Akita, and Iwate) in northern Japan, between April 2019 and August 2022. Trichinella larvae were detected in 2.5% (6/236) of the brown bears and 0.9% (1/117) of the Japanese black bears. Sequence analysis using two genetic loci, the internal transcribed spacer region of nuclear ribosomal DNA and the mitochondrial cytochrome c oxidase subunit I gene, revealed that the larvae collected from the seven infected bears were identical to one of the two haplotypes of Trichinella T9. The prevalence of Trichinella T9 is low but is maintained in bears in the Hokkaido and Iwate prefectures suggesting that undercooked meat from these animals could cause human infection. Thus, continued health education campaigns are needed to raise awareness of the potential risk of trichinellosis among hunters, meat suppliers, consumers, and local governmental health agencies.

2.
Int J Surg Case Rep ; 102: 107808, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36495753

ABSTRACT

INTRODUCTION: Laparoscopic cholecystectomy is a safe and standard procedure, but serious bile duct injury may occur due to anatomical anomalies of the biliary tract, especially the accessory hepatic duct. The use of intraoperative fluorescence cholangiography with indocyanine green during laparoscopic cholecystectomy can reportedly prevent bile duct injury. PRESENTATION OF CASE: A 55-year-old woman with upper abdominal pain was referred to our hospital. Laboratory investigations revealed elevated leukocytes and biliary enzymes, while computed tomography demonstrated increased fatty tissue density around the gallbladder. Magnetic resonance cholangiopancreatography and drip infusion cholangiographic-computed tomography showed that the cystic duct drained into an accessory hepatic duct. Due to the diagnosis of cholelithiasis with a biliary anomaly, we performed laparoscopic cholecystectomy using fluorescence cholangiography with indocyanine green. We were able to recognize the accessory hepatic duct and cystic duct, then safely dissect the cystic duct without bile duct injury. DISCUSSION: Laparoscopic cholecystectomy is generally regarded as a safe procedure, but complications and even mortalities can arise in patients with anatomical anomalies of the biliary tract. The aid of intraoperative fluorescence cholangiography with indocyanine green allowed to recognize and identify the accessory hepatic duct and cystic duct, allowing us to operate without injury to the bile duct. CONCLUSIONS: Our experience supports the ease of use, safety, and effectivity of fluorescence cholangiography with indocyanine green. This may become the optimal standard technique to prevent bile duct injury.

3.
Surg Case Rep ; 8(1): 169, 2022 Sep 14.
Article in English | MEDLINE | ID: mdl-36103018

ABSTRACT

BACKGROUND: Pancreatic cancer (PC) is a highly lethal malignancy, even if surgical resection is possible (median survival: < 30 months). The prognosis of borderline resectable pancreatic cancer (BR-PC) is even worse. There is no clear consensus on the optimal treatment strategy, including pre/postoperative therapy, for BR-PC. We report a patient with BR-PC who achieved clinical partial response with neoadjuvant chemoradiation therapy (NACRT) and underwent curative resection, resulting in pathological complete response (pCR). CASE PRESENTATION: A 71-year-old man with jaundice and liver dysfunction was referred to our department because of a 48-mm hypo-vascular mass in the pancreatic head with obstruction of the pancreatic and bile ducts and infiltration of superior mesenteric vein and portal vein. The lesion was identified as atypical cells which suggested adenocarcinoma by biopsy, and he was administered NACRT: gemcitabine and nab-paclitaxel, following S-1 and intensity modulated radiation therapy. After reduction in the tumor size (clinical partial response), pancreaticoduodenectomy was performed, and pCR achieved. Postoperative adjuvant chemotherapy with S-1 was initially administered and the patient is currently alive with no recurrence as of 2 years after surgery. CONCLUSIONS: NACRT is a potentially useful treatment for BR-PC that may lead to pCR and help improve prognosis.

4.
J Exp Psychol Anim Learn Cogn ; 48(2): 123-134, 2022 Apr.
Article in English | MEDLINE | ID: mdl-35533105

ABSTRACT

A Müller-Lyer figure consists only of a line and arrowheads located at both ends of the line. Many comparative studies have reported that animals perceive Müller-Lyer illusion as humans, but few have used appropriate experimental designs to verify whether animal subjects actually respond to line length alone. The present study investigated whether budgerigars (Melopsittacus undulatus) can perceive the Müller-Lyer illusion by using a method that addresses this problem. Four budgerigars were trained to select a long or short line (counterbalanced across subjects) from two horizontal lines. Next, the same task was conducted using two lines, one of which was situated between arrowheads pointing either right (>>) or left (<<). In the final training phase, the arrowheads were replaced with those pointing inward (><) or outward (<>). The performance of each subject toward each stimulus set of these trainings suggested that they did not determine the length of the line by including the arrowheads. In the test phase, response tendencies to the four figures were compared. Results suggested that budgerigars perceive the Müller-Lyer illusion in the same direction as humans; however, its magnitude is larger than that of humans. (PsycInfo Database Record (c) 2022 APA, all rights reserved).


Subject(s)
Melopsittacus , Optical Illusions , Animals , Humans , Optical Illusions/physiology
5.
Gan To Kagaku Ryoho ; 49(13): 1768-1770, 2022 Dec.
Article in Japanese | MEDLINE | ID: mdl-36732993

ABSTRACT

A 68-year-old woman with a chief complaint of obstructive jaundice was referred to our hospital. She was diagnosed with gallbladder cancer with invasion to the liver, extrahepatic bile duct, right hepatic artery and portal vein. After endoscopic retrograde biliary drainage, she received chemotherapy with gemcitabine and cisplatin. After 9 courses, the size of the tumor and the lymph nodes decreased, and we planned surgery. There were no unresectable factors, and the right hepatic artery and portal vein were detached from the tumor. We performed a subtotal stomach-preserving pancreaticoduodenectomy and gallbladder bed resection. We then performed adjuvant chemotherapy with S-1 for 1 year. The patient remains alive without recurrence, 5 years after the surgery. We report the case of advanced gallbladder cancer with downstaging after GC therapy.


Subject(s)
Gallbladder Neoplasms , Female , Humans , Aged , Gallbladder Neoplasms/drug therapy , Gallbladder Neoplasms/surgery , Gallbladder Neoplasms/pathology , Gemcitabine , Cisplatin , Combined Modality Therapy , Antineoplastic Combined Chemotherapy Protocols/therapeutic use
6.
J Exp Anal Behav ; 116(1): 82-95, 2021 07.
Article in English | MEDLINE | ID: mdl-34105175

ABSTRACT

Four pigeons were exposed to a tandem variable-interval (VI) fixed-ratio (FR) schedule in the presence of a 50-pixel (about 15 mm) square or an 80-pixel (about 24 mm) square and to a tandem VI differential-reinforcement-of-low-rate (DRL) schedule when a second 80-pixel or 50-pixel square was present. The values of the VI and FR schedules were adjusted to equate reinforcement rates in the two tandem schedules. Following this, a square-size continuum generalization test was administered under a fixed-interval (FI) schedule or extinction. In the first testing session, response frequency was a graded function of the similarity of the test stimuli to the training stimuli for all pigeons. These systematic generalization gradients persisted longer under the FI schedule than under extinction.


Subject(s)
Generalization, Psychological , Generalization, Stimulus , Animals , Columbidae , Conditioning, Operant , Reinforcement Schedule , Reinforcement, Psychology
7.
Anim Cogn ; 21(2): 207-217, 2018 03.
Article in English | MEDLINE | ID: mdl-29230574

ABSTRACT

Despite their impressive cognitive abilities, avian species have shown less evidence for metacognition than mammals. We suspect that commonly used tasks such as matching to sample might be too demanding to allow metacognitive processing within birds' working memory. Here, we examined whether pigeons could control their behavior as a function of knowledge levels on a three-item sequence learning task, a reference memory task supposedly requiring fewer working memory resources. The experiment used two types of lists differing in familiarity. One was familiar to the pigeons through repeated exposure, whereas the other was novel in every new session. In test sessions, pigeons could choose between a trial with a hint specifying the next item to peck and one with no hint. However, successful responses in trials with a hint resulted in lowered rates of primary reinforcement: .60 in the first test and .75 in the second. Results showed that two of four pigeons chose the trial with a hint significantly more often before receiving a novel list than the familiar list in the four sessions of the first test, and three did so in the second test. Impressively, one bird showed robust evidence in the very first sessions in both tests. These results suggest that pigeons may monitor their long-term knowledge states and thereby control their environment before starting to solve a task.


Subject(s)
Columbidae/physiology , Memory, Short-Term , Metacognition , Animals , Behavior, Animal , Conditioning, Operant , Cues , Female , Male
8.
Drug Des Devel Ther ; 11: 1871-1879, 2017.
Article in English | MEDLINE | ID: mdl-28694687

ABSTRACT

PURPOSE: The purpose of this study was to investigate the efficacy and safety of the administration of retinol palmitate (VApal) ophthalmic solution (500 IU/mL) for the treatment of patients with dry eye. PATIENTS AND METHODS: This study included 66 patients with dry eye. After a 2-week washout period, patients were randomized (1:1) into either a VApal ophthalmic solution or a placebo group, and a single drop of either solution was administered six times daily for 4 weeks. Efficacy measures were 12 subjective symptoms, rose bengal (RB) and fluorescein staining scores, tear film breakup time, and tear secretion. Safety measures included clinical blood and urine analyses and adverse event recordings. RESULTS: In comparisons of the two groups, the mean change in RB staining score from baseline was significantly lower in the VApal group at 2 and 4 weeks (P<0.05 and P<0.01, respectively). Furthermore, the fluorescein clearance rate (fluorescein staining score) was significantly higher in the VApal group at 4 weeks (P<0.05). The VApal group showed a significant improvement in blurred vision at 1 and 2 weeks (P<0.01 and P<0.05, respectively), and the mean change in the total score for subjective symptoms from baseline was significantly lower in the VApal group at 1 week (P<0.05). In before- and after-intervention comparisons, the fluorescein and RB staining scores showed improvement in both groups. Improvement was noted for 11 subjective symptoms in the VApal group and for seven symptoms in the placebo group. No significant differences in adverse events and reactions were found between the groups. CONCLUSION: VApal ophthalmic solution (500 IU/mL) is safe and effective for the treatment of patients with dry eye.


Subject(s)
Antioxidants/adverse effects , Antioxidants/therapeutic use , Dry Eye Syndromes/drug therapy , Vitamin A/analogs & derivatives , Adolescent , Adult , Aged , Antioxidants/administration & dosage , Diterpenes , Double-Blind Method , Female , Humans , Japan , Male , Middle Aged , Ophthalmic Solutions , Retinyl Esters , Tears/drug effects , Treatment Outcome , Vision Disorders/drug therapy , Vitamin A/administration & dosage , Vitamin A/adverse effects , Vitamin A/therapeutic use , Young Adult
9.
Vision Res ; 103: 32-40, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25152320

ABSTRACT

Retinotopic encoding is preserved in primate visual cortex. However, several physiological and psychophysical studies have revealed that visual processes can be disengaged from retinotopic coordinates. We examined whether this non-retinotopic processing is common to humans and pigeons, two visually dominant vertebrate species with similar retinotopic organizations in their brains. We used a variant of Ternus-Pikler stimulus as a litmus test for non-retinotopic processing. Six humans and four pigeons were required to discriminate the rotational direction of a target disk placed among linearly arranged non-rotating disks. When all disks flickered in synchrony (a blank screen was inserted between the stimulus presentations) and moved in tandem back and forth, target localization was hampered in humans but not pigeons (Experiment 1). The duration of the blank screen (Experiment 2) and the connection between the disks (Experiment 3) did not affect the pigeons' performance. These results suggest that non-retinotopic processing in human vision is not a feature of pigeon vision, which is instead strictly retinotopic in case of motion. This may reflect the different mechanisms for stimulus selection in both species, in which local motion signals were pooled at later stages of visual processing in humans, but the signals were selected at early stages in pigeons.


Subject(s)
Motion Perception/physiology , Retina/physiology , Adult , Analysis of Variance , Animals , Columbidae , Discrimination, Psychological/physiology , Humans , Photic Stimulation/methods , Psychophysics , Species Specificity , Young Adult
10.
Anim Cogn ; 17(2): 471-81, 2014 Mar.
Article in English | MEDLINE | ID: mdl-23995772

ABSTRACT

A disk surrounded by smaller disks looks larger, and one surrounded by larger disks looks smaller than reality. This visual illusion, called the Ebbinghaus-Titchener illusion, remains one of the strongest and most robust illusions induced by contrast with the surrounding stimuli in humans. In the present study, we asked whether bantams would perceive this illusion. We trained three bantams to classify six diameters of target disks surrounded by inducer disks of a constant diameter into "small" or "large". In the test that followed, the diameters of the inducer disks were systematically changed. The results showed that the Ebbinghaus-Titchener figures also induce a strong illusion in bantams, but in the other direction, that is, bantams perceive a target disk surrounded by smaller disks to be smaller than it really is and vice versa. Possible confounding factors, such as the gap between target disk and inducer disks and the weighted sum of surface of these figural elements, could not account for the subjects' biased responses. Taken together with the pigeon study by Nakamura et al. (J Exp Psychol Anim Behav Process 34:375-387 2008), these results show that bantams as well as pigeons perceive an illusion induced by assimilation effects, not by contrast ones, for the Ebbinghaus-Titchener types of illusory figures. Perhaps perceptual processes underlying such illusory perception (i.e., lack of contrast effects) shown in bantams and pigeons may be partly shared among other avian species.


Subject(s)
Chickens/physiology , Optical Illusions , Animals , Conditioning, Operant/physiology , Discrimination, Psychological , Female , Male , Optical Illusions/physiology , Pattern Recognition, Physiological , Photic Stimulation
11.
Anim Cogn ; 16(2): 211-21, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23065184

ABSTRACT

Seeking information in uncertain situations has been interpreted as evidence of metacognitive abilities. We examined whether pigeons could monitor their own knowledge states and seek new information when in need. In Experiment 1, we required the pigeons to learn novel sequences of responses for various trios of illustrations. On half of the trials, subjects were given the opportunity to ask for "hints" as to the next correct response in a sequence. If the subjects completed a trial correctly without any hints, they were rewarded with food and light. If the subjects sought one or more hints during the course of completing a trial correctly, they were rewarded either with food and light, or with light only. Incorrect responses resulted in a time-out. We analyzed when the pigeons sought hints. Two of four pigeons sought hints in early sessions more often than in the final sessions of learning novel sequences, and the frequency of hint-seeking was inversely correlated with accuracy on those trials in which hints were unavailable. In Experiment 2, however, the pigeons failed to generalize their "hint-seeking" behavior in a novel situation involving visual search as the primary task. In sum, the results suggest that this species might have an ability to differentiate between their own cognitive states of knowing and not knowing, although the evidence is inconclusive.


Subject(s)
Behavior, Animal , Columbidae , Information Seeking Behavior , Animals , Cognition , Conditioning, Operant , Male , Reward
12.
Anim Cogn ; 16(1): 109-15, 2013 Jan.
Article in English | MEDLINE | ID: mdl-22960804

ABSTRACT

Although pigeons have been shown to be susceptible to several size and length illusions, other avian species have not been tested intensively for illusory perception. Here we report how bantams perceive the Zöllner figure, in which parallel lines look nonparallel due to short crosshatches superimposed on the lines. Watanabe et al. (Cognition 119:137-141, 2011) showed that pigeons, like humans, perceived parallel lines as nonparallel but that the orientation of subjective convergence was opposite to that of humans. We trained three bantams to peck at the narrower (or wider) of the two gaps at the end of a pair of nonparallel lines. After adapting them to target lines with randomly oriented crosshatches (which result in no apparent illusion to humans), we tested the bantams' responses on randomly inserted probe trials, in which crosshatches that should induce the standard Zöllner-like illusion for humans replaced the randomly oriented ones. The results suggested bantams, like pigeons, perceive a reversed Zöllner illusion.


Subject(s)
Chickens , Optical Illusions , Visual Perception , Animals , Female , Male
13.
J Comp Psychol ; 125(4): 411-9, 2011 Nov.
Article in English | MEDLINE | ID: mdl-22142039

ABSTRACT

Humans perceive a line touching an edge of a large rectangle longer than the reality. Kanizsa (1979) has suggested that this illusion occurs because we perceive that the line is partly "hidden" behind the rectangle and automatically completes it. We tested whether bantams (Gallus gallus domesticus) would experience this perceptual phenomenon using a line classification task on the touch monitor, which was used in our previous study with rhesus monkeys and pigeons (Fujita, 2001). We trained three bantams to classify six lengths of black target lines into two categories, "short" or "long," ignoring a gray rectangle (Experiment 1) or a gray area (i.e., a left or a right half of the monitor was filled with gray; Experiment 2) located at the same distance (8 pixels) from the target line. In the test, the gap between the line and the gray rectangle (or area) sometimes changed (0, 4, or 8 pixels; we labeled these stimuli as G0, G4, and G8 respectively). Both of the two successfully trained bantams showed an illusion for G0, but the direction of illusion was reversed; that is, they judged the line in G0 to be "shorter" than that in G4 and G8. Further analyses proved that neither the gaps between the target line and the gray rectangle nor the total widths of the stimuli could account for the bantams' responses. These results suggest that bantams do not complete the "occluded" portion even when identification of its shape is not required.


Subject(s)
Chickens , Pattern Recognition, Visual , Animals , Chickens/physiology , Discrimination Learning , Discrimination, Psychological , Female , Male , Photic Stimulation , Psychomotor Performance
14.
Cognition ; 119(1): 137-41, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21109240

ABSTRACT

Pigeons are susceptible to several size and length illusions, but in some cases the bias has been shown to be opposite to that seen in humans. To further investigate how their perceptual system works, we asked how pigeons perceive orientation illusions. We used the Zöllner illusion, in which parallel lines look non-parallel due to series of short crosshatches superimposed on the lines. First, we trained six birds to peck at the narrower (or wider) of the two gaps at the end of a pair of non-parallel target lines. After adapting the subjects to target lines with randomly oriented crosshatches (which result in no illusion at least to humans), we tested the pigeons' responses on randomly inserted probe trials, in which crosshatches that should induce the standard Zöllner-like illusion for humans replaced the random-oriented ones. The results suggested that pigeons do perceive an illusion from Zöllner figures, but in the direction opposite to that of humans. We propose that pigeons, contrary to humans, may assimilate the two lines of different orientations (each main line and crosshatch), which results in underestimation of acute angles, and this in turn may lead to a reversed Zöllner illusion. Such assimilation dominance appears consistent with previous reports obtained for line length and size illusions in this species.


Subject(s)
Columbidae/physiology , Optical Illusions/physiology , Orientation/physiology , Visual Perception/physiology , Animals , Male , Pattern Recognition, Visual/physiology , Photic Stimulation
15.
Anim Cogn ; 14(1): 83-93, 2011 Jan.
Article in English | MEDLINE | ID: mdl-20665063

ABSTRACT

Rhesus monkeys are known to recognize confidence about their immediate perceptual and cognitive decisions by using a betting procedure (Son and Kornell in The missing link in cognition: origins of self-reflective consciousness. Oxford University Press, New York, pp 296-320, 2005; Kornell et al. in Psychol Sci 18:64-71, 2007). In this report, we examined whether this ability is shared in two avian species (pigeons and bantams) in order to know how widespread this metacognitive ability is among animals. We trained pigeons and bantams to search for a differently colored disk (target) among others (distracters) displayed on a touch-sensitive monitor. In test, the subjects were required to choose one of two confidence icons, "risk" and "safe", after the visual search. A peck at the "risk" icon after a correct response in the visual search (i.e., a peck at the target) was reinforced by food and light, while that after an incorrect response (i.e., a peck at a distracter) resulted in a timeout. A peck at the "safe" icon was always reinforced by food and light, or by light only, regardless of the visual search result. The percentages of "safe" choices after incorrect responses were higher than after correct responses in all six pigeons and two of three bantams. This behavior generalized to novel stimuli in some subjects, and even to a novel line-classification task in a pigeon. These results suggest that these two distantly related avian species have in common a metacognitive ability that allows them to recognize confidence about their immediate perceptual decisions.


Subject(s)
Cognition , Decision Making , Animals , Chickens , Columbidae , Visual Perception
16.
J Biol Chem ; 285(52): 40864-78, 2010 Dec 24.
Article in English | MEDLINE | ID: mdl-20929857

ABSTRACT

Cell surface glycans play pivotal roles in immune cell trafficking and immunity. Here we present an efficient method for generating anti-carbohydrate monoclonal antibodies (mAbs) using gene-targeted mice and describe critical glycans in lymphocyte homing. We immunized sulfotransferase GlcNAc6ST-1 and GlcNAc6ST-2 doubly deficient mice with sulfotransferase-overexpressing Chinese hamster ovary cells and generated two mAbs, termed S1 and S2. Both S1 and S2 bound high endothelial venules (HEVs) in the lymphoid organs of humans and wild-type mice, but not in those of doubly deficient mice. Glycan array analysis indicated that both S1 and S2 specifically bound 6-sulfo sialyl Lewis X and its defucosylated structure. Interestingly, S2 inhibited lymphocyte homing to peripheral lymph nodes by 95%, whereas S1 inhibited it by only 25%. S2 also significantly inhibited contact hypersensitivity responses and L-selectin-dependent leukocyte adhesion to HEVs. Immunohistochemical and Western blot analyses indicated that S1 preferentially bound sulfated O-glycans, whereas S2 bound both sulfated N- and O-glycans in HEVs. Furthermore, S2 strongly inhibited the N-glycan-dependent residual lymphocyte homing in mutant mice lacking sulfated O-glycans, indicating the importance of both sulfated N- and O-glycans in lymphocyte homing. Thus, the two mAbs generated by a novel method revealed the cooperative function of sulfated N- and O-glycans in lymphocyte homing and immune surveillance.


Subject(s)
Antibodies, Monoclonal/immunology , Glycoproteins/immunology , Lymphocytes/immunology , Oligosaccharides/immunology , Animals , Antibodies, Monoclonal/pharmacology , CHO Cells , Cell Adhesion/drug effects , Cell Adhesion/immunology , Cricetinae , Cricetulus , Glycoproteins/genetics , Glycoproteins/metabolism , Humans , Immunologic Surveillance/drug effects , Immunologic Surveillance/immunology , Lewis Blood Group Antigens , Lymphocytes/enzymology , Mice , Mice, Knockout , Oligosaccharides/biosynthesis , Oligosaccharides/genetics , Sulfotransferases/biosynthesis , Sulfotransferases/genetics , Sulfotransferases/immunology
17.
J Comp Psychol ; 124(3): 331-5, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20695664

ABSTRACT

Whereas many mammals (some primates and mice) experience amodal completion, previous data split for avian species. However, experimental procedures have been quite different among the species, and thus a direct comparison of various avian species in the same experimental situation is needed. We tested whether bantams (Gallus gallus domesticus) would complete partly occluded figures using a visual search task on the touch monitor, which was successfully used in our previous study with pigeons. First, we trained 3 participants to search for a notched red diamond (a target) among complete diamonds (distracters). Next, white squares accompanied each figure with a small gap of a fixed size. In test, the location of the accompanying white squares sometimes changed. In some trials, the white squares exactly covered, or "occluded," the notched portion of the target. Humans are known to have great difficulty in finding such targets due to "automatic" completion of the notched part. However, bantams met no such difficulty at all. This result and the demonstration by Forkman (1998) of hens' amodal completion of figures placed on a perspective background, suggest that the perspective cue may have an important role in amodal completion in this species.


Subject(s)
Attention , Chickens/physiology , Color Perception , Orientation , Pattern Recognition, Visual , Perceptual Closure , Perceptual Masking , Animals , Male , Problem Solving , Reaction Time , Species Specificity
18.
J Comp Psychol ; 123(3): 287-94, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19685970

ABSTRACT

Nakamura, Fujita, Ushitani, & Miyata (2006) have shown that pigeons perceive the standard Müller-Lyer illusion. In this report, the authors examined effects of bracket sizes on perception of this illusion in pigeons (Columba livia) and humans (Homo sapiens). In Experiment 1, three pigeons were retrained to classify six lengths of target lines into "long" and "short" by pecking two keys on the monitor, ignoring the two brackets oriented toward the same direction. In the tests that followed, the standard Müller-Lyer figures of different bracket sizes were presented. All birds chose "long" more frequently for the figures having inward-pointing brackets (><) than for those having outward-pointing brackets (<>), regardless of bracket sizes. The overestimation of the target lines of inward-pointing figures continued to increase in pigeons, whereas it decreased as the bracket size became longer in humans (Experiment 2). The results suggest that these two species perceive the standard Müller-Lyer illusion with long brackets in different ways. Perhaps pigeons might not perceive illusions induced by contrast with the surrounding stimuli.


Subject(s)
Columbidae , Optical Illusions , Orientation , Pattern Recognition, Visual , Size Perception , Adult , Aged , Aged, 80 and over , Animals , Attention , Discrimination Learning , Female , Humans , Male , Middle Aged , Psychophysics , Reversal Learning , Species Specificity , Young Adult
19.
Percept Mot Skills ; 108(1): 239-50, 2009 Feb.
Article in English | MEDLINE | ID: mdl-19425465

ABSTRACT

Nakamura, et al. recently showed that pigeons experience the standard Müller-Lyer illusion but not the reversed illusion induced by detaching the arrowheads from the target line. This study re-examined pigeons' perception of this reversed figure by using the stimuli known to induce the maximal contrast effect in humans (Fellows, 1967). Pigeons were retrained to classify six lengths of target lines into "long" and "short" categories by pecking two keys on the monitor, ignoring the two brackets so placed that these would not induce an illusion. In the test that followed, two birds responses were not affected by directions of arrowheads, as shown in the previous study. The third pigeon significantly chose "long" for inward-pointing brackets figures (> <) more frequently than for outward-pointing (< >), that is, the direction of illusion was reversed from what is expected in humans. These results suggest that pigeons may not experience illusions induced by contrast with the surrounding stimuli.


Subject(s)
Columbidae/physiology , Optical Illusions/physiology , Pattern Recognition, Visual/physiology , Animals , Choice Behavior/physiology , Conditioning, Operant/physiology , Contrast Sensitivity/physiology , Discrimination Learning/physiology , Female , Humans , Male , Reinforcement Schedule
20.
J Exp Psychol Anim Behav Process ; 34(3): 375-87, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18665720

ABSTRACT

A target circle surrounded by larger "inducer" circles looks smaller, and one surrounded by smaller circles looks larger than they really are. This is the Ebbinghaus-Titchener illusion, which remains one of the strongest and most robust of contrast illusions. Although there have been many studies on this illusion in humans, virtually none have addressed how nonhuman animals perceive the same figures. Here the authors show that the Ebbinghaus-Titchener figures also induce a strong illusion in pigeons but, surprisingly, in the other direction; that is, all five successfully trained pigeons judged the target circle surrounded by larger circles to be larger than it really is and vice versa. Further analyses proved that neither the gaps between target and inducer circles nor the cumulative weighted surface of these figural elements could account for the birds' responses. Pigeons are known to show similarities to humans on various cognitive and perceptual tasks including concept formation, short-term memory, and some visual illusions. Our results, taken together with pigeons' previously demonstrated failure at visual completion, provide strong evidence that pigeons may actually experience a visual world too different for us to imagine.


Subject(s)
Optical Illusions , Pattern Recognition, Visual , Animals , Columbidae , Discrimination Learning , Female , Hominidae , Humans , Judgment , Male
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