Unraveling the linguistic nature of specific autobiographical memories using a computerized classification algorithm

In the present study, we explored the linguistic nature of specific memories generated with the Autobiographical Memory Test (AMT) by developing a computerized classifier that distinguishes between specific and nonspecific memories. The AMT is regarded as one of the most important assessment tools to study memory dysfunctions (e.g., difficulty recalling the specific details of memories) in psychopathology. In Study 1, we utilized the Japanese corpus data of 12,400 cue-recalled memories tagged with observer-rated specificity. We extracted linguistic features of particular relevance to memory specificity, such as past tense, negation, and adverbial words and phrases pertaining to time and location. On the basis of these features, a support vector machine (SVM) was trained to classify the memories into specific and nonspecific categories, which achieved an area under the curve (AUC) of .92 in a performance test. In Study 2, the trained SVM was tested in terms of its robustness in classifying novel memories (n?= 8,478) that were retrieved in response to cue words that were different from those used in Study 1. The SVM showed an AUC of .89 in classifying the new memories. In Study 3, we extended the binary SVM to a five-class classification of the AMT, which achieved 64%–65% classification accuracy, against the chance level (20%) in the performance tests. Our data suggest that memory specificity can be identified with a relatively small number of words, capturing the universal linguistic features of memory specificity across memories in diverse contents.     

Flexible route selection by pigeons (Columba livia) on a computerized multi-goal navigation task with and without an "obstacle"

The ability to select efficient routes while reaching several locations, in situations addressed as the "traveling salesperson problem (TSP)", seems to play an important role in the lives of nonhuman species as well as humans. One of our previous studies with pigeons (Columba livia) used different variations of computerized navigation tasks to move a target to one or more goals, and showed that the birds consistently exhibited tendencies to visit the nearest goal first (Miyata & Fujita, 2010). Is this inflexible tendency consistent across all situations, or is it abandoned if it leads to a nonefficient strategy? The present study compared pigeons' route selection strategies in two-goal navigation tasks with and without having an L-shaped line as an obstacle barrier between the starting location of the target and the nearer goal. The pigeons frequently started by visiting the nearer goal in trials with no obstacles, whereas in trials having obstacles the birds often visited the farther goal first. For the detour trials with obstacles, the birds started from visiting the farther goal significantly more often than chance, even though disparity between the two traveling sequences was relatively small. The data demonstrated a case in which a tendency to visit the nearest goal was flexibly abandoned when the route required a detour behavior. Detailed analyses of the movement paths further suggest that the pigeons made decisions to choose a farther goal during the initial few steps, although a past history of reinforcement to avoid the barrier might have guided the birds' behavior.     

Reading words with jumbled characters in Japanese

Rayner, et al. (2006) was replicated with 36 Japanese undergraduates who read Japanese sentences in which characters were transposed in one word at the beginning, middle, or end. The same pattern of reading delays in relation to transposition location was found but in smaller magnitude. Transposition of characters at the beginning of words caused the largest delay in reading.     

Perceptual chunking in the self-produced songs of Bengalese finches (Lonchura striata var. domestica)

Like humans, songbirds, including Bengalese finches, have hierarchical structures in their vocalizations. When humans perceive a sentence, processing occurs in phrase units, not words. In this study, we investigated whether songbirds also perceive their songs by chunks (clusters of song notes) rather than single song notes. We trained male Bengalese finches to react to a short noise in a Go/NoGo task. We then superimposed the noise onto recordings of their own songs and examined whether the reaction time was affected by the location of the short noise, that is, whether the noise was placed between chunks or in the middle of a chunk. The subjects’ reaction times to the noise in the middle of a chunk were significantly longer than those to the noise placed between chunks. This result was not observed, however, when the songs were played in reverse. We thus concluded that Bengalese finches perceive their songs by chunks rather than single notes.     

Pigeons perceive the Ebbinghaus-Titchener circles as an assimilation illusion

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.     

Pigeons (Columba livia) plan future moves on computerized maze tasks

Planning, the internal process of formulating an organized method about one's future behavior, should be advantageous for non-human animals as well as for humans. However, little is known about this process in avian species. We examined planning processes in pigeons (Columba livia) using a computerized maze task. In Experiment 1, we found that the pigeons plan their next one step, and in some cases even correctly adjust their actions after change of goal locations, while performing on a plus-shaped maze. We also showed that the pigeons might even plan two steps on familiar, well-practiced mazes. In Experiment 2, we discovered that the subjects plan the direction they would go first before starting to solve a four-arm shuriken (a Japanese traditional throwing knife)-shaped maze. The birds also corrected their previously planned actions after change of goal locations. Our results from these experiments suggest that planning ahead is within the cognitive capacity of a "bird brain", and that it may be more widespread in the animal kingdom than has been presumed.     

Conformity among cowitnesses sharing same or different information about an event in experimental collaborative eyewitness testimony

Using the Mori technique in which two different movies presented on the same screen were viewed separately by two groups without their noticing the duality, two experiments were carried out with 138 undergraduates in groups of varying sizes to examine the effects of cowitnesses with the same or different information on these witnesses' memory distortion. Exp. 1 investigated the cowitness effects in a one-versus-two situation, while Exp. 2 investigated the effects in a two-versus-two situation. Analysis showed isolated eyewitnesses who had no supporting cowitnesses changed their minds more frequently toward the majority and, when they had a cowitness who shared the same information, they tended to stick to their original reports even after being confronted with conflicting information in a discussion.     

Sport-specific decision-making in a Go/NoGo reaction task: difference among nonathletes and baseball and basketball players

The present study examined whether Go/Nogo reaction time (RT) is a relevant index of the sport expertise relating to sport-specific decision-making. 57 male university students, 20 basketball players, 24 baseball players, and 13 sedentary students as a control group, performed a Simple RT task and Go/NoGo RT task which had baseball specific stimulus-response relations. Participants in baseball and basketball differed further in having high, medium, and low experience in the sports. For comparisons across sports, the basketball and the baseball players had significantly shorter reaction times than the nonathletes in both tasks. In contrast, reaction times varied significantly across experience for the baseball players in the Go/NoGo RT task but not for basketball players. These results suggested that Go/NoGo RT could be used as an index of expertise for sport-specific decision-making, if stimulus-response relation in Go/NoGo RT task has a natural relation for a particular sport-domain.     

You say tomato? Collaborative remembering leads to more false memories for intimate couples than for strangers

Research on memory conformity shows that collaborative remembering--typically in the form of discussion--can influence people's memories. One question that remains is whether it matters with whom we discuss our memories. To address this question we compared people's memories for an event after they discussed that event with either their romantic partner or a stranger. Pairs of subjects watched slightly different versions of a movie, and then discussed some details from the movie, but not others. Subjects were better at remembering non-discussed details than discussed details: when remembering discussed details they incorrectly reported information from their partner's version instead of their own. In addition, subjects who discussed the event with their romantic partner (rather than with a stranger) were even more likely to report false memories. We discuss our findings in relation to other research on memory conformity, social influences on false memories, and memory systems within romantic relationships.     

The BAI–PC as a Screen for Anxiety, Depression, and PTSD in Primary Care

Despite the prevalence of psychiatric disorders in medical settings, mental health problems often go undetected and patients do not receive appropriate treatment. The main goal of this study is to provide additional information about the Beck Anxiety Inventory – Primary Care (BAI–PC), a brief instrument that screens for patients with anxiety. This study provides information on the performance of the BAI–PC as a screening instrument for depression and PTSD in addition to its original purpose as a screening instrument for anxiety. This efficient tool can identify patients who can benefit from effective psychological treatments and facilitate referrals to psychologists working in medical settings.