<div>While cognitive control enables the selection of goal-relevant responses, metacontrol enables the selection of context-appropriate control operations. In task switching, metacontrol modulates task-switching efficiency by retrieving the associations between a contextual cue and a particular cognitive control demand. While the automatic retrieval of cognitive control is appealing due to its time and energy efficiency, the effects of different contextual cues have been shown in separate studies and appear to have different characteristics. Here, we devised a single task-switching paradigm to test whether we can observe both list-wide and item-specific metacontrol within subjects. In two experiments, we demonstrated reduced switch costs in lists associated with a high probability of switching as compared with lists with a low probability of switching (i.e., a list-wide switch probability [LWSP] effect). Similarly, we observed an analogous item-specific switch probability (ISSP) effect such that items associated with a high probability of switching incurred smaller switch costs as compared with items associated with a low probability of switching. We also confirmed that both list-wide and item-specific switch probability effects were not dependent on lower-level stimulus-response associations. However, the LWSP and the ISSP effects were uncorrelated, suggesting a lack of dependence. Together, these findings suggest that there are two distinct modes of metacontrol that are deployed in a context-sensitive manner in order to adapt to specific cognitive demands.</div>

<p>Several researchers have claimed that passively viewing manipulable objects results in automatic motor activation of affordances regardless of intention to act upon an object. Support for the <i>automatic activation account </i>stems primarily from findings using stimulus-response compatibility paradigms in which responses are fastest when there is correspondence between one’s response hand and an object’s handle. Counter to this view is the <i>spatial coding account</i>, which suggests that past findings are a result of abstract spatial codes stemming from salient object properties and their left-right correspondence with responses. Although there is now considerable support for this account, there has been little attention paid to determining whether evidence in favor of the automatic activation account will be evident after accounting for the spatial issues demonstrated by the spatial coding account.</p><p>The present study involved five experiments conducted to bridge this gap in two steps. First, I aimed to demonstrate the importance of considering spatial issues and left-right correspondence when studying object-based motor activation by numerous objects championed by past researchers who attempted to similarly address the aforementioned issue (Experiments 1 and 2). Second, I sought to determine whether evidence favoring the automatic activation account could be obtained when the possibility for left-right correspondence was absent in a novel set of stimuli created specifically for this purpose (Experiments 3, 4, and 5).</p><p>Experiment 1 examined a stimulus set that some researchers have suggested can more definitively tease apart evidence for automatic activation from the influence of spatial factors studies. Experiment 2 was more narrowly focused and investigated a single object presented in different horizontal orientations. These experiments effectively demonstrated the importance of giving more consideration to the nature of the stimuli used in object-based compatibility studies and how they are presented. The results of Experiment 1 suggest that a stimulus set that has been claimed to sidestep spatial confounds does not, in fact, do so. Moreover, Experiment 2 demonstrated that performance could be influenced by simple rotation of the object to which a response was required.</p><p>Having established the importance of controlling the stimuli used to investigate automatic activation of afforded responses, I turned to determining whether a novel stimulus set would yield findings favoring the automatic activation account even after accounting for left-right correspondence (Experiments 3, 4, and 5). Three sets of novel object stimuli were developed that do not allow for left-right correspondence and could iteratively assess support for the automatic activation account based on criteria for activation that have been put forth in the literature. The three sets of stimuli contained no information about shape nor functionality (i.e., silhouette iteration) or information about shape and functionality (i.e., functional iteration), or they were an intermediate between the two other types (i.e., intermediate iteration).</p><p>Critically, the three latter experiments progressively approached the conditions that researchers have suggested are ideal for automatic activation of afforded responses to occur. Experiment 3 tasked participants with completing a color discrimination task in which they viewed only one of the three object iterations and responded with button presses. Experiment 4 used the same experimental configuration, but instead, required participants to respond with a grasping response. Finally, Experiment 5 required participants to complete a reach-and-grasp response in an object discrimination task using both the silhouette and functional iterations.</p><p>Across Experiments 3, 4, and 5, no support for the automatic activation account of afforded responses was found. Although the automatic activation account would predict that individuals should be fastest at responding to the functional stimuli than to the other two object iterations, no such evidence was observed. Given that the possibility for left-right correspondence was removed from the novel stimulus set studied here, these results provide indirect support for the spatial coding account of prior results and further indicate that past findings favoring the automatic activation account have largely been a result of left-right correspondence. </p>

A warning signal that precedes an imperative stimulus by a certain length of time (the foreperiod) can accelerate responses (foreperiod effect). Plotting reaction time (RT) as a function of foreperiod results in a “U”-shape curve when the foreperiod is fixed in a trial block but manipulated across blocks. When the foreperiod is varied within a block, the foreperiod-RT function is usually negative, with the foreperiod effect modulated by both the current foreperiod and the foreperiod in the prior trial (sequential foreperiod effect). This sequential effect was found to be robust at the shorter foreperiod while diminished at the longer foreperiod. Capizzi et al. (2015) used a non-aging foreperiod distribution and found an increasing foreperiod-RT function (consistent with that in a fixed-foreperiod paradigm) and a sequential effect equal for different foreperiods. They thus proposed a repetition priming account for the sequential foreperiod effect. I conducted three experiments, aiming to test this repetition priming account and to rebuild the connection between the fixed- and variable-foreperiod paradigms. Experiment 1 attempted to replicate Capizzi et al. in a choice-reaction task scenario and found an increasing foreperiod-RT function but a larger sequential effect at the shorter foreperiod. Experiment 2 examined the priming account in a short-foreperiod context and found a decreasing foreperiod-RT function with a larger sequential effect at the shorter foreperiod. Experiment 3 detected a larger sequential effect in general by increasing the difference in duration between the foreperiods that were used in Experiment 2. The current study provided converging evidence that with a non-aging foreperiod distribution the foreperiod-RT function in a variable-foreperiod paradigm shares the same direction as that in a fixed-foreperiod paradigm. However, instead of following Capizzi et al.’s account, the size of the sequential foreperiod effect in general was found to be modulated by the difference in duration between the foreperiods while the relative sizes were determined by the proportions of different foreperiods.

<div>There is evidence that after a person chooses between two items, the chosen item is more memorable than the unchosen alternative. This is known as the chosen-item effect (Coverdale & Nairne, 2019). We frequently make choices, such as which restaurant to visit for dinner, or which brand of shampoo to buy, and what we choose in these situations can influence what we remember. In the field of consumer behavior, it is believed that memory for brand names and products influences consumer purchasing behaviors. As such, we were interested in investigating whether the chosen-item effect could be extended to memory for brands and product names. If choosing a brand name or product makes it more memorable, then companies can apply the chosen-item effect to improve an item’s memorability and potentially increase sales of that item. In three experiments we investigated whether the chosen-item effect can be extended to memory for products (Experiment 1) and brand names (Experiment 2 & 4b) and found a mnemonic benefit for items that were chosen over those that were not chosen.</div><div>In addition to the relationship between choice and memory, there is also a relationship between choice and value. We hypothesized that people would be willing to pay more for items that they have previously chosen, in addition to having better memory for them. We conducted a second set of experiments (Experiments 3 & 4a) to investigate whether the chosen-item effect extends beyond memory to value. We found that items that have previously been chosen were not perceived as being more valuable than those that were not chosen. This finding has theoretical implications for research on the mechanism(s) responsible for the chosen-item effect.</div>

<div><div><div><p>The brain dynamically alters its production of flexible behavior: cognitive flexibility increases when demand is high. In task switching experiments, past exposure to a high demand for flexibility in conjunction with specific temporal contexts leads to learned switch readiness such that future exposures to those contexts will cue flexibility. According to a recent proposal (Dreisbach & Fröber, 2019), learned switch readiness following switch demands is supported by a concurrent activation (CA) cognitive mechanism whereby both sets of task rules are kept available in working memory despite only using one at a time. This can be differentiated from a competing candidate mechanism, working memory updating (WMU) thresholds which determine the ease of replacing one task’s rules with another. The WMU mechanism is expected to cause a global increase in flexibility while CA is conceptualized as limited to task-specific associations. To test whether learned switch readiness represents a global or limited change in the cognitive system, I conducted two experiments that both involved learning switch readiness in one context and generalizing it in another. In Experiment 1, I replicated and extended findings that switch probability manipulations can modulate voluntary switch rates (VSR), indicating one type of generalizability. However, in Experiment 2, I found that flexibility learned through switch probability manipulations did not transfer to new tasks when the task rules were changed but contextual cues remained the same, demonstrating a limit: learned switch readiness does not generalize across tasks. These findings together suggest that CA is likely the mechanism behind learned switch readiness.</p></div></div></div>

The aim of this thesis was to investigate the input-specificity of sensory-induced plasticity in humans. This was achieved by varying the characteristics of sine gratings so that they selectively targeted distinct populations of neurons in the visual cortex. In Experiments 1-3, specificity was investigated with electroencephalography using horizontally- and vertically-oriented sine gratings (Experiment 1) or gratings of differing spatial frequency (Experiments 2 & 3). Increases in the N1b potential were observed only for sine gratings that were the same in orientation or spatial frequency as that used as the tetanus, suggesting that the potentiation is specific to the visual pathways stimulated during the induction of the tetanus. However, the increase in the amplitude of the N1b in Experiment 1 was not maintained when tested again at 50 minutes post-tetanus. This may have been due to depotentiation caused by the temporal frequency of stimulus presentation in the first post-tetanus block. To try to circumvent this potential confound, immediate and maintained (tested 30 minutes post-tetanus) spatial-frequency-specific potentiation were tested separately in Experiments 2 and 3, respectively. Experiment 3 demonstrated that the increased N1b was maintained for up to half an hour post-tetanus. In addition, the findings from Experiment 1, as well as the pattern of results from Experiments 2 and 3, indicate that the potentiation must be occurring in the visual cortex rather than further upstream at the lateral geniculate nucleus. In Experiment 4 functional magnetic resonance imaging was used to more accurately localise where these plastic changes were taking place using sine gratings of differing spatial frequency. A small, focal post-tetanic increase in the blood-oxygen-level-dependent (BOLD) response was observed for the tetanised grating in the right temporo-parieto-occipital junction. For the non-tetanised grating, decreases in BOLD were found in the primary visual cortex and bilaterally in the cuneus and pre-cuneus. These decreases may have been due to inhibitory interconnections between neurons tuned to different spatial frequencies. These data indicate that tetanic sensory stimulation selectively targets and potentiates specific populations of neurons in the visual cortex.

The aim of this thesis was to investigate the input-specificity of sensory-induced plasticity in humans. This was achieved by varying the characteristics of sine gratings so that they selectively targeted distinct populations of neurons in the visual cortex. In Experiments 1-3, specificity was investigated with electroencephalography using horizontally- and vertically-oriented sine gratings (Experiment 1) or gratings of differing spatial frequency (Experiments 2 & 3). Increases in the N1b potential were observed only for sine gratings that were the same in orientation or spatial frequency as that used as the tetanus, suggesting that the potentiation is specific to the visual pathways stimulated during the induction of the tetanus. However, the increase in the amplitude of the N1b in Experiment 1 was not maintained when tested again at 50 minutes post-tetanus. This may have been due to depotentiation caused by the temporal frequency of stimulus presentation in the first post-tetanus block. To try to circumvent this potential confound, immediate and maintained (tested 30 minutes post-tetanus) spatial-frequency-specific potentiation were tested separately in Experiments 2 and 3, respectively. Experiment 3 demonstrated that the increased N1b was maintained for up to half an hour post-tetanus. In addition, the findings from Experiment 1, as well as the pattern of results from Experiments 2 and 3, indicate that the potentiation must be occurring in the visual cortex rather than further upstream at the lateral geniculate nucleus. In Experiment 4 functional magnetic resonance imaging was used to more accurately localise where these plastic changes were taking place using sine gratings of differing spatial frequency. A small, focal post-tetanic increase in the blood-oxygen-level-dependent (BOLD) response was observed for the tetanised grating in the right temporo-parieto-occipital junction. For the non-tetanised grating, decreases in BOLD were found in the primary visual cortex and bilaterally in the cuneus and pre-cuneus. These decreases may have been due to inhibitory interconnections between neurons tuned to different spatial frequencies. These data indicate that tetanic sensory stimulation selectively targets and potentiates specific populations of neurons in the visual cortex.

The aim of this thesis was to investigate the input-specificity of sensory-induced plasticity in humans. This was achieved by varying the characteristics of sine gratings so that they selectively targeted distinct populations of neurons in the visual cortex. In Experiments 1-3, specificity was investigated with electroencephalography using horizontally- and vertically-oriented sine gratings (Experiment 1) or gratings of differing spatial frequency (Experiments 2 & 3). Increases in the N1b potential were observed only for sine gratings that were the same in orientation or spatial frequency as that used as the tetanus, suggesting that the potentiation is specific to the visual pathways stimulated during the induction of the tetanus. However, the increase in the amplitude of the N1b in Experiment 1 was not maintained when tested again at 50 minutes post-tetanus. This may have been due to depotentiation caused by the temporal frequency of stimulus presentation in the first post-tetanus block. To try to circumvent this potential confound, immediate and maintained (tested 30 minutes post-tetanus) spatial-frequency-specific potentiation were tested separately in Experiments 2 and 3, respectively. Experiment 3 demonstrated that the increased N1b was maintained for up to half an hour post-tetanus. In addition, the findings from Experiment 1, as well as the pattern of results from Experiments 2 and 3, indicate that the potentiation must be occurring in the visual cortex rather than further upstream at the lateral geniculate nucleus. In Experiment 4 functional magnetic resonance imaging was used to more accurately localise where these plastic changes were taking place using sine gratings of differing spatial frequency. A small, focal post-tetanic increase in the blood-oxygen-level-dependent (BOLD) response was observed for the tetanised grating in the right temporo-parieto-occipital junction. For the non-tetanised grating, decreases in BOLD were found in the primary visual cortex and bilaterally in the cuneus and pre-cuneus. These decreases may have been due to inhibitory interconnections between neurons tuned to different spatial frequencies. These data indicate that tetanic sensory stimulation selectively targets and potentiates specific populations of neurons in the visual cortex.

The aim of this thesis was to investigate the input-specificity of sensory-induced plasticity in humans. This was achieved by varying the characteristics of sine gratings so that they selectively targeted distinct populations of neurons in the visual cortex. In Experiments 1-3, specificity was investigated with electroencephalography using horizontally- and vertically-oriented sine gratings (Experiment 1) or gratings of differing spatial frequency (Experiments 2 & 3). Increases in the N1b potential were observed only for sine gratings that were the same in orientation or spatial frequency as that used as the tetanus, suggesting that the potentiation is specific to the visual pathways stimulated during the induction of the tetanus. However, the increase in the amplitude of the N1b in Experiment 1 was not maintained when tested again at 50 minutes post-tetanus. This may have been due to depotentiation caused by the temporal frequency of stimulus presentation in the first post-tetanus block. To try to circumvent this potential confound, immediate and maintained (tested 30 minutes post-tetanus) spatial-frequency-specific potentiation were tested separately in Experiments 2 and 3, respectively. Experiment 3 demonstrated that the increased N1b was maintained for up to half an hour post-tetanus. In addition, the findings from Experiment 1, as well as the pattern of results from Experiments 2 and 3, indicate that the potentiation must be occurring in the visual cortex rather than further upstream at the lateral geniculate nucleus. In Experiment 4 functional magnetic resonance imaging was used to more accurately localise where these plastic changes were taking place using sine gratings of differing spatial frequency. A small, focal post-tetanic increase in the blood-oxygen-level-dependent (BOLD) response was observed for the tetanised grating in the right temporo-parieto-occipital junction. For the non-tetanised grating, decreases in BOLD were found in the primary visual cortex and bilaterally in the cuneus and pre-cuneus. These decreases may have been due to inhibitory interconnections between neurons tuned to different spatial frequencies. These data indicate that tetanic sensory stimulation selectively targets and potentiates specific populations of neurons in the visual cortex.

The aim of this thesis was to investigate the input-specificity of sensory-induced plasticity in humans. This was achieved by varying the characteristics of sine gratings so that they selectively targeted distinct populations of neurons in the visual cortex. In Experiments 1-3, specificity was investigated with electroencephalography using horizontally- and vertically-oriented sine gratings (Experiment 1) or gratings of differing spatial frequency (Experiments 2 & 3). Increases in the N1b potential were observed only for sine gratings that were the same in orientation or spatial frequency as that used as the tetanus, suggesting that the potentiation is specific to the visual pathways stimulated during the induction of the tetanus. However, the increase in the amplitude of the N1b in Experiment 1 was not maintained when tested again at 50 minutes post-tetanus. This may have been due to depotentiation caused by the temporal frequency of stimulus presentation in the first post-tetanus block. To try to circumvent this potential confound, immediate and maintained (tested 30 minutes post-tetanus) spatial-frequency-specific potentiation were tested separately in Experiments 2 and 3, respectively. Experiment 3 demonstrated that the increased N1b was maintained for up to half an hour post-tetanus. In addition, the findings from Experiment 1, as well as the pattern of results from Experiments 2 and 3, indicate that the potentiation must be occurring in the visual cortex rather than further upstream at the lateral geniculate nucleus. In Experiment 4 functional magnetic resonance imaging was used to more accurately localise where these plastic changes were taking place using sine gratings of differing spatial frequency. A small, focal post-tetanic increase in the blood-oxygen-level-dependent (BOLD) response was observed for the tetanised grating in the right temporo-parieto-occipital junction. For the non-tetanised grating, decreases in BOLD were found in the primary visual cortex and bilaterally in the cuneus and pre-cuneus. These decreases may have been due to inhibitory interconnections between neurons tuned to different spatial frequencies. These data indicate that tetanic sensory stimulation selectively targets and potentiates specific populations of neurons in the visual cortex.