Some determinants of remote behavioral history effects in humans

Undergraduates were exposed to a series of reinforcement schedules: first, to a fixed-ratio (FR) schedule in the presence of one stimulus and to a differential-reinforcement-of-low-rate (DRL) schedule in the presence of another (multiple FR DRL training), then to a fixed-interval (FI) schedule in the presence of a third stimulus (FI baseline), next to the FI schedule under the stimuli previously correlated with the FR and DRL schedules (multiple FI FI testing), and, finally, to a single session of the multiple FR DRL schedule again (multiple FR DRL testing). Response rates during the multiple FI FI schedule were higher under the former FR stimulus than under the former DRL stimulus. This effect of remote histories was prolonged when either the number of FI-baseline sessions was small or zero, or the time interval between the multiple FR DRL training and the multiple FI FI testing was short. Response rates under these two stimuli converged with continued exposure to the multiple FI FI schedule in most cases, but quickly differentiated when the schedule returned to the multiple FR DRL.     

Adaptive memory: Stereotype activation is not enough

Studies have shown that survival processing leads to superior memorability. The aim of the present study was to examine whether this survival recall advantage might result from stereotype activation. To test this hypothesis, we conducted a pilot study and two experiments in which participants were primed with stereotypes (Experiment 1, professor and elderly person; Experiment 2, survival-stereotype). In Experiment 1, 120 undergraduates were randomly assigned to a survival, professor stereotype, elderly person stereotype, or moving scenario and rated words for their relevance to the imagined scenario. In Experiment 2, 75 undergraduates were given a survival, survival-stereotype (based on our pilot study), or moving scenario. Both experiments showed that survival processing leads to a greater recall advantage over the stereotype groups and control group. These data indicate that the mere activation of stereotypes cannot explain the survival recall advantage.     

Childhood Peer Status and Adult Susceptibility to Anxiety and Depression. A 30-Year Hospital Follow-up

This study examined the extent to which sixth grade peer status could predict anxiety and/or depression in 5,242 women and 5,004 men who were born in 1953 and whose hospital records were followed up from 1973–2003. The data used was the Stockholm Birth Cohort Study. While no association could be established for men, results indicated that women who held low peer status positions in childhood were at a considerably higher risk of anxiety and/or depression later in life compared to women in average status positions. Women who held popular positions during childhood did not differ significantly from their average counterparts. These findings persisted after adjusting for family- and child-related problem-load, perceived security at school, family constellation, socioeconomic status as well as the child’s cognitive ability, ninth grade school marks and continuance to upper secondary school.     

No postnatal maternal effect on male aggressiveness in wild-derived strains of house mice

Male aggressiveness is a complex behavior influenced by a number of genetic and non-genetic factors. Traditionally, the contribution of each of these factors has been established from experiments using artificially selected strains for high/low aggressive phenotypes. However, little is known about the factors underlying aggressive behavior in natural populations. In this study, we assess the influence of genetic background vs. postnatal maternal environment using a set of cross-fostering experiments between two wild-derived inbred strains, displaying high (STRA, derived from Mus musculus domesticus) and low (BUSNA, derived from Mus musculus musculus) levels of aggressiveness. The role of maternal environment was tested in males with the same genetic background (i.e. strain origin) reared under three different conditions: unfostered (weaned by mother), infostered (weaned by an unfamiliar dam from the same strain), and cross-fostered (weaned by a dam from a different strain). All males were tested against non-aggressive opponents from the A/J inbred strain. Resource-holding potential was assessed through body weight gains and territory ownership. The STRA males were shown to be aggressive in both neutral cage and resident-intruder tests. On the contrary, the BUSNA males were less aggressive in all tests. We did not find a significant effect of postnatal maternal environment; however, we detected significant maternal effect on body weight with differences between the strains, fostering type and interactions between these factors. We conclude that the aggressiveness preserved in the two strains has significant genetic component whose genetic basis can be dissected by quantitative trait loci analysis.     

The mental lexicon is fully specified: evidence from eye-tracking

Four visual-world experiments, in which listeners heard spoken words and saw printed words, compared an optimal-perception account with the theory of phonological underspecification. This theory argues that default phonological features are not specified in the mental lexicon, leading to asymmetric lexical matching: Mismatching input (pin) activates lexical entries with underspecified coronal stops (tin), but lexical entries with specified labial stops (pin) are not activated by mismatching input (tin). The eye-tracking data failed to show such a pattern. Although words that were phonologically similar to the spoken target attracted more looks than did unrelated distractors, this effect was symmetric in Experiment 1 with minimal pairs (tin-pin) and in Experiments 2 and 3 with words with an onset overlap (peacock-teacake). Experiment 4 revealed that /t/-initial words were looked at more frequently if the spoken input mismatched only in terms of place than if it mismatched in place and voice, contrary to the assumption that /t/ is unspecified for place and voice. These results show that speech perception uses signal-driven information to the fullest, as was predicted by an optimal perception account.     

The incongruency advantage for environmental sounds presented in natural auditory scenes

The effect of context on the identification of common environmental sounds (e.g., dogs barking or cars honking) was tested by embedding them in familiar auditory background scenes (street ambience, restaurants). Initial results with subjects trained on both the scenes and the sounds to be identified showed a significant advantage of about five percentage points better accuracy for sounds that were contextually incongruous with the background scene (e.g., a rooster crowing in a hospital). Further studies with naive (untrained) listeners showed that this incongruency advantage (IA) is level-dependent: there is no advantage for incongruent sounds lower than a Sound/Scene ratio (So/Sc) of -7.5 dB, but there is about five percentage points better accuracy for sounds with greater So/Sc. Testing a new group of trained listeners on a larger corpus of sounds and scenes showed that the effect is robust and not confined to a specific stimulus set. Modeling using spectral-temporal measures showed that neither analyses based on acoustic features, nor semantic assessments of sound-scene congruency can account for this difference, indicating the IA is a complex effect, possibly arising from the sensitivity of the auditory system to new and unexpected events, under particular listening conditions.     

Eye movements and display change detection during reading

In the boundary change paradigm (Rayner, 1975), when a reader's eyes cross an invisible boundary location, a preview word is replaced by a target word. Readers are generally unaware of such changes due to saccadic suppression. However, some readers detect changes on a few trials and a small percentage of them detect many changes. Two experiments are reported in which we combined eye movement data with signal detection analyses to investigate display change detection. On each trial, readers had to indicate if they saw a display change in addition to reading for meaning. On half the trials the display change occurred during the saccade (immediate condition); on the other half, it was slowed by 15-25 ms (delay condition) to increase the likelihood that a change would be detected. Sentences were presented in an alternating case fashion allowing us to investigate the influence of both letter identity and case. In the immediate condition, change detection was higher when letters changed than when case changed corroborating findings that word processing utilizes abstract (case independent) letter identities. However, in the delay condition (where d' was much higher than the immediate condition), detection was equal for letter and case changes. The results of both experiments indicate that sensitivity to display changes was related to how close the eyes were to the invalid preview on the fixation prior to the display change, as well as the timing of the completion of this change relative to the start of the post-change fixation.